MID SEMESTER TEST

1. Pure substance x is solid at room temperature. if the substance is heated to 230 C is melted gradually. if then cooled to room temperature, the liquid can not be frozen.
a. is it possible x of an element or a compound. explain it!
b. Does it chemical change occured? if so can it be said undergo an endotherm changing, based on the information provided?
c. can it be said that the liquid is an element, based on the information provided.

2. When a candle that weighs 10 g is burned in oxygen, carbon dioxide and water vapor formed by combustion the weight more than 10 g. was this case match with the law of conservation of mass. Explain it!

3. When carbon burns in oxygen under limited number, it will form two gaseous compounds. Suggest the way to differentiate the two compounds with one another.

4. after Mendeleev compiled the periodic table, he concluded that the atomic weights of certain elements was wrong ruling, and this conclusion was apparently correct. How Mendeleev was able to predict the several atomic weights were wrong? why his predictions are not always right. Explain it!

5. When an aqueous solution of Merkuri chloride is added an aqueous solution of silver nitrate, a white solid forms. Identify the white solid and write the balanced equation for the reaction that occurs.

Answer :

1.a. According to me,The pure substance X is a compound,because the boiling point of the substance is very high, this possibility is an ionic compound. when frozen at room temperature the substance can not be frozen, because freezing of these compounds are also very high.so the pure substance x is a compound.

b.yes it can be said of any change in the chemical reaction.because after cooled to room temperature, a substance that is formed can not be restored to its original form or substance can be said to have a chemical change to form a new type of substance and its chemical composition of substances originally were. such as burnt paper and sugar are heated.can be said that the reaction that occurs is the endothermic reaction because the reaction is accompanied by heat transfer from the environment to the system (heat absorbed by the system from its environment) and is characterized by a decrease in ambient temperature around the system.

c.the liquid can be regarded as an element,because pure substance x is a compound that will break down into smaller compounds or elements when heated to a certain temperature (called the decomposition temperature).

2.when the candle burned with oxygen to form 10 grams of gas, namely carbon dioxide and 10 grams of water vapor, and formed a number of energy (heat and light). if the whole combustion accommodated and weighed, surely its mass equals the mass plus the mass of oxygen candles in use on burning it. reaction of candle burning:

2C20H42 (s) +61O2I (g )----> 40CO2 (g) +42 H2O (g)
10 grams 10 grams
substances before the reaction mass = mass of substance after the reaction

Law of Conservation of Mass
"The mass of the substance before the reaction is equal to mass substance of reaction"

3.Carbon forms two well-known oxides, carbon monoxide , CO, and carbon dioxide , CO2.
• Carbon monoxide.

Carbon monoxide is produced when graphite (one of the naturally occurring forms of elemental carbon) is heated or burned in a limited amount of oxygen.The reaction of steam with red-hot coke also produces carbon monoxide along with hydrogen gas(H2).(Coke is the Impure carbon residue resulting from the burning of coal.) This mixture of CO and H 2 is Called a water gas and is used as an industrial fuel. In the laboratory, carbon monoxide is prepared by heating formic acid, HCOOH, or oxalic acid, H 2 C 2 O 4 , with concentrated sulfuric acid, H 2 SO 4 .The sulfuric acid removes the elements of water (ie, H 2 O) from the formic or oxalic acid and absorbs the water produced. Because carbon monoxide burns readily in oxygen to produce carbon dioxide,

2CO + O 2 ® 2CO 2

it is useful as a gaseous fuel.It is also useful as a metallurgical reducing agent at high temperatures because it reduces many metal oxides to the elemental metal. For example, copper(II) oxide, CuO, and iron(III) oxide, Fe 2 O 3 , both are reduced to the metal by carbon monoxide.

Carbon monoxide is an extremely dangerous poison.Because it is an odourless and tasteless gas, it gives no warning of its presence.It binds to the hemoglobin in blood to form a stable compound.that is so that it cannot be broken down by body processes.When the hemoglobin is combined with carbon monoxide, it cannot combine with oxygen; this destroys the ability of hemoglobin to carry oxygen to all essential parts of the body.Suffocation can occur if sufficient amounts of carbon monoxide are present to form complexes with the hemoglobin.

•Carbon dioxide.
Carbon dioxide is produced when any form of carbon or almost any carbon compound is burned in an excess of oxygen.Many metal carbonates liberate CO 2 when they are heated.For example, calcium carbonate (CaCO 3 ) produces carbon dioxide and calcium oxide (CaO).

CaCO 3 + heat ® CO 2 + CaO

The fermentation of glucose (a sugar) during the preparation of ethanol, the alcohol found in beverages such as beer and wine, produces large quantities of CO 2 as a by-product.

C 6 H 12 O 6 ® 2C 2 H 5 OH+ 2CO 2

glucoseethanol

In the laboratory CO 2 can be prepared by adding a metal carbonate to an aqueous acid; eg,

CaCO 3 + 2H 3 O+ ® Ca²+ "" + 3H 2 O+ CO 2 .

Carbon dioxide is a colourless and essentially odourless gas That is 1.5 times as dense as water. It is not toxic, although a large concentration could result in suffocation simply by causing a lack of oxygen in the body.All carbonated beverages contain dissolved CO 2 ; hence the name carbonated.One liter (1:06 quarts) of water at 20 ° C dissolves 0.9 liter of CO 2 at one atmosphere, forming carbonic acid (H 2 CO 3 , discussed below in the section Oxyacids and Their salts), the which has a mildly acidic (sour) taste.Solid CO 2 sublimes at normal atmospheric pressure.Thus, solid CO 2 , Called dry ice, is a Valuable refrigerant That is always free of the liquid form. Carbon dioxide is also used as a fire extinguisher, because most substances do not burn in it, and it is readily available and inexpensive.Water containing as little as 2.5 percent CO 2 extinguishes a flame.

4. Dmitry Ivanovich concluded that the properties of elements are periodic function of the relative atomic mass. That is, if the elements are arranged according to the relative atomic mass increases, then the specific properties will be repeated periodically. Mendeleev placed elements with similar characteristics in a class of vertical columns called groups. Mendeleev emptied several places. This is done to determine the similarity of traits in the classroom. Mendeleev also predicted the nature of the elements that have not known it. The forecast is based on the known properties of other elements, which is adjacent either horizontally or upright. elements are expected to be found, and it accords well with the predictions of Mendeleev. One example is a germanium (Ge), which was discovered in 1886, which by Mendeleev named ekasilikon. The weakness of this theory still contains elements of the larger mass is located in front of the element whose mass is smaller. Co: Tellurium (te) = 128 in kiriIodin (I) = 127. This is because the elements that have similarity properties are placed in one class. The weakness of this theory is the atomic mass correction. Previous atomic mass. In a previous atomic mass = 76-113. Be apart, from 13.5 to 9. N 120-240.

Mendeleev was right to put tellurium in the same group with sulfur and oxygen; however, strict order of atomic weights According to the best information available Had he would have required iodine (127) to come before tellurium (128).e was Suspicious of this apparent inversion of atomic weight order; as it Happens, the atomic weights Had Mendeleev available to him agree with the currently accepted values.

5.HgCl2 + 2AgNO3 ---> Hg (NO3) 2 + 2AgCl
The resulting white powder is silver nitrate.

Stoichiometry

1.1 Mole concept & Avogadro's constant

1.1.1: Apply the mole concept to substances.

A mole is equivalent to 6.022 x 1023 (Avogadro's constant) units. Chemists refer to a mole of something much as we refer to a dozen eggs; it is a convenient unit for counting. The periodic table provides molar masses, i.e. the number of grams of an element equivalent to one mole of atoms of that specific element. This can be extrapolated to molecules of known molecular formula.

1.1.2: Determine the number of particles and the amount of substance (in moles).

Number of moles = mass / molar mass (Usually found on periodic table). The coefficients in chemical equations give the molar ratios of reactants and products i.e. 2A + 3B → C. There is 2/3 as much A as B, and 3 times more B than C involved in the reaction. Assuming the reaction goes to completion, there must be 3/2 times as much B as A for neither to remain. If this ratio is not followed, one will be a limiting reactant, and so the reaction will have some of the other reactant left over when it completes.

1.2 Formulae

1.2.1: Define the term molar mass (M) and calculate the mass of one mole of a species.

The molar mass (M) is the mass of one mole's worth of a substance. To find the mass, multiply the amount of moles by the molar mass.

1.2.2: Atomic mass, Molecular Mass, Formula Mass

The molar mass can be found for the periodic table, and will give the mass for 1 mol of the species (or rather the average accounting for different isotopes and their relative abundance).

1.2.3: Define the terms relative molecular mass (Mr) and relative atomic mass (Ar)

Mr is the ratio between the molar masses of two species. Ar is the ratio of the number of atoms between two species. These two ratios will be equal. there should be more metal compare to cupper.

1.2.4: The difference between moles and mass

The number of moles refers to the amount of the substance, every mol being 6.02 x 1023 individual elements. Mass is the property which results in 'weight' in the presence of gravity. Given a molar mass, M a mass m and a number of mols n then n = m / M.

1.2.5: The difference between the molecular formula and the empirical formula

An 'empirical formula' is the formula describing the different atoms present in a molecules, and their ratios, but not the actual number present. For example, AxByCz could be an empirical formula if x, y, and z are in lowest common terms. The molar mass can then be used to calculate the actual numbers of each atom present per molecule. The empirical formula can be determined by percentage composition, or anything else which gives the ratios of atoms present. A 'molecular formula', on the other hand, has the actual number of atoms present in each molecule. It will be an integer multiple of the empirical formula. For example, A2xB2yC2z.

Example:
If you are given the empirical formula with an equation CH3, and a mass of 30.08 g mol-1. What is the molecular formula of this compound?
We will compare the molecular mass of the molecular formula, 30.08 g mol-1, to that of the empirical formula, found to be 15.04 g mol-1. By dividing, we find the ratio to be 2, meaning that the molecular formula must be 2 times as large as the empirical formula. The molecular formula is therefore C2H6.

1.3 Chemical Equations

Chemical equations are a convenient, standardised system for describing chemical reactions. They contain the following information.

* The type of reactants consumed and products formed
* The relative amounts of reactants and products
* The electrical charges on ions
* The physical state of each species (e.g. solid, liquid, gas)
* The reaction conditions (e.g. temperature, catalysts)

The final two points are optional and sometimes omitted.
Anatomy of an Equation

http://upload.wikimedia.org/wikibooks/en/math/b/2/5/b25a60e361846b9010875cfdb3aedbec.png

Hydrogen gas and chlorine gas will react vigorously to produce hydrogen chloride gas. The equation above illustrates this reaction. The reactants, hydrogen and chlorine, are written on the left and the products (hydrogen chloride) on the right. The large number 2 in front of HCl indicates that two molecules of HCl are produced for each 1 molecule of hydrogen and chlorine gas consumed. The 2 in subscript below H indicates that there are two hydrogen atoms in each molecule of hydrogen gas. Finally, the (g) symbols subscript to each species indicates that they are gases.

Reacting Species

Species in a chemical reaction is a general term used to mean atoms, molecules or ions. A species can contain more than one chemical element (HCl, for example, contains hydrogen and chlorine). Each species in a chemical equation is written:

http://upload.wikimedia.org/wikibooks/en/math/2/0/c/20c7976579a8c1ddc719cb8285c88009.png

E is the chemical symbol for the element, x is the number of atoms of that element in the species and y is the charge (if it is an ion).

For example, ethanol would be written C2H6O because each molecule contains 2 carbon, 6 hydrogen and 1 oxygen atom. A magnesium ion would be written Mg2 + because it has a double positive charge. Finally, an ammonium ion would be written [NH4] + because each molecule contains 1 nitrogen and 4 hydrogen atoms and has a charge of 1+.

Coefficients

The numbers in front of each species have a very important meaning - they indicate the relative amounts of the atoms that react. The number infront of each species is called a coefficient. In the above equation, for example, one H2 molecule reacts with one Cl2 molecule to produce two molecules of HCl. This can also be interpreted as moles (i.e. 1 mol H2 and 1 mol Cl2 produces 2 mol HCl).
Other Information

Occasionally, other information about a chemical reaction will be supplied in an equation (such as temperature or other reaction conditions). This information is often written above the reaction arrow. We will ignore this for now, as it only complicates matters (and it's hard to draw in TeX :).

1.3.1 : The mole ratio of two species in a chemical equation is the ratio of their coefficients...ie aX + bY → cZ : The ratio of X/Y is a/b, Y/Z = b/c etc.

Chemical equations are useful because they give the relative amounts of the substances that react in a chemical equation. For example, from the chemical equation for the formation of ammonia, we can see that one mole of nitrogen gas will combine with three moles of hydrogen gas to form two moles of ammonia gas.

http://upload.wikimedia.org/wikibooks/en/math/8/4/5/84526dc79e50100874ac97b6acc91d6e.png

1.3.2 : Balancing equations...change only the coefficients, not the subscripts to make sure all atoms, and charge is conserved (half equations can be balanced by addition of electrons to either side...2 half equations can be added by making the number of electrons equal in each, then vertically adding.)

In some cases, however, we may not know the relative amounts of each substance that reacts. Fortunately, we can always find the correct coefficients of an equation (the relative amounts of each reactant and product) by applying the law of conservation of matter. Because matter can neither be created nor destroyed, the total number of each atom on one side of the equation must be the same as the total on the other. This process of finding the coefficients is known as balancing the equation.

For example, assume in the above equation that we do not know how many moles of ammonia gas will be produced:

http://upload.wikimedia.org/wikibooks/en/math/5/6/2/562755b825e6229fea990ade8f36ce48.png

From the left side of this equation, we see that there are 2 atoms of nitrogen gas in the molecule N2 (2 atoms per molecule x 1 molecule), and 6 atoms of hydrogen gas in the 3 H2 molecules (2 atoms per molecule x 3 molecules). Because of the law of conservation of matter, there must also be 2 atoms nitrogen gas and 6 atoms of hydrogen gas on the right side. Since each molecule of the the resultant ammonia gas (NH3) contains 1 atom of nitrogen and 3 atoms of hydrogen, 2 molecules are needed to obtain 2 atoms of nitrogen and 6 atoms of hydrogen.

In a similar manner, you can use the law of conservation of matter to solve equations containing a greater number of unknown coefficients (the relative amounts of each reactant and product), or even subscripts (the number of each element in a molecule) on either side of the equation:

http://upload.wikimedia.org/wikibooks/en/math/5/6/2/562755b825e6229fea990ade8f36ce48.png

1.3.3 : State symbols -- (s)-Solid , (l)-liquid, (g)-gas, (aq)-aqueous solution...i.e. something dissolved in water. Should be included in all chemical reactions (but won't be penalized).
\hbox{E}_{(state)} \,

E is the chemical symbol for the element and (state) is the physical state.

Examples

http://upload.wikimedia.org/wikibooks/en/math/d/b/7/db7673c35ce210db95c76e54199ca71e.png

Above is the equation for burning methane gas (CH4) in the presence of oxygen (O2) to form carbon dioxide and water: CO2 and H2O respectively.

http://upload.wikimedia.org/wikibooks/en/math/0/c/2/0c210a60200dbb51b973522bbb876ef8.png

This is a precipitation reaction in which dissolved lead cations and iodide anions combine to form a solid yellow precipitate of lead iodide (an ionic solid).

Simple Formulas

Moles to Particles: number of moles x (6.02 x 1023/1 mole)= number of Particles

ex: 2.50 mol Zn x (6.02*1023 atoms of Zn/1 mol Zn)= 1.51 x 1024 atoms of Zn


Particles to Moles: number of Particles * (1 mole/6.02 x 1023)= number of moles

ex: 1.204 x 1024 atoms Ag * (1 mol/6.02 x 1023 atoms Ag)= 2 moles of Ag


Moles to Mass: number of moles x (molar mass/ 1 mole)= number of grams (or other unit of measurement)

ex: 3.57 mol Al x (26.982 g Al/ 1 mol Al)= 53.964 g


Mass to Moles: number of grams * (1 mole/ molar mass)= number of moles

ex: 25.5 g Ag * (1 mol Ag/ 107.868 g Ag)= 0.236 mol

*
o
+ to find molar mass

ex: Na2CO3 = 2(mass of Na)+ mass of C + 3(mass of O)

=2(22.990)+12.011+3(15.999)

=45.98+12.001+47.997

=105.99 g Na2CO3

1.4 Mass relationships in chemical reactions

1.4.1 : Mass is conserved throughout reactions. This fact allows masses to be calculated based on other masses in the reaction eg burning Mg in air to produce MgO and so to find the mass or Mg present in the original sample (ie purity)...can be extended to concentrations...ie titration.

1.4.2 : When a reaction contains several reactants, some may be in excess...is more is present that can be used in the reaction. The first reactant to run out is the limiting reagent (or reactant). Knowing the number of mols of the limiting reagent allows all other species to be calculated, and so the yield, and remaining quantities of other reactants.

1.5 Solutions

1.5.1

* Solvent - the fluid you're dissolving in e.g. water.
* Solute - something which has been dissolved to form a solution e.g. an ionic compound such as sodium hydroxide.
* Solution - a mixture of solvent and solute.
* Concentration - the amount of solute per volume of solution. Measured in moles per dm3 (i.e. moles per liter) or grams per liter.

1.5.2 : Apply the equation concentration = moles/volume...rather obvious from the units of concentration, but remember to convert everything into the same units.

1.5.3 : Use chemical equations to relate the amount of one species to the amounts of others.

TOPIC 1: QUANTITATIVE CHEMISTRY

Formula and Valency of Ions

SOME COMMON CATIONS

Ammonium NH4+ Barium Ba+2
Hydrogen H+ Calcium Ca+2
Lithium Li+ Copper Cu+2
Potassium K+ Lead Pb+2
Sodium Na+ Magnesium Mg+2
Silver Ag+ Mercury Hg+2
Nickel Ni+2
Aluminium Al+3 Zinc Zn+2

N.B. Many metals, including some of those above, show more than one valency. The valency is then always given with the name of the compound. It is written in Roman Numerals after the name of the metal.

e.g. Iron may be Fe+2 or Fe+3

Iron II Chloride is Fe+2(Cl-)2

Iron III Chloride is Fe+3(Cl-)3

Other examples which you may meet are

Chromium II or Chromium III Cr+2 or Cr+3

Manganese II or Manganese IV Mn+2 or Mn+4

Tin II or Tin IV Sn+2 or Sn+4

Lead II or Lead IV Pb+2 or Pb+4

Some Common Anions

Aluminate Al(OH)4- (aqueous) or AlO2- (crystalline) TetraHydroxoZincate Zn(OH)4-2 (aqueous) or ZnO2-2 (crystalline)
Bromide Br- Chromate (VI) CrO4-2
Chlorate (V) ClO3- DiChromate (VI) Cr2O7-2
Chloride Cl- Ethanedioate (oxalate) C2O4-2
Cyanide CN- Oxide O-2
Ethanoate (acetate) CH3CO2- Peroxide O2-2
Ethoxide C2H5O- Sulphate SO4-2
Fluoride F- Sulphide S-2
Hydride H- Sulphite SO3-2
HydrogenCarbonate HCO3- ThioSulphate S2O3-2
HydrogenSulphate HSO4- HexaCyanoFerrate III [Fe(CN)6]-3
Hydroxide OH- Carbonate CO3-2
HypoChlorite ClO-
Iodide I- Nitride N-3
Methanoate HCO2- Phosphate PO4-3
Nitrate NO3- HexaCyanoFerrate II [Fe(CN)6]-4
Nitrite NO2-
Manganate (VII) (PerManganate) MnO4-
ThioCyanate SCN-

Rules of thumb: Anions consisting of just one element have names ending -ide.

* Anions consisting of an element plus oxygen have names ending in -ate.

* Notable exception: OH- is hydroxide, not 'hydrate'.

* If an element has two anions whose names should end in -ate, the one with fewer oxygens ends in -ite.

EXERCISE 1

Work out the formula for the following ionic chemicals

1. Zinc Chloride ZnCl2
2. Sodium Oxide Na2O
3. Aluminium Fluoride AlF3
4. Iron III Chloride FeCl3
5. Aluminium Oxide Al2O3
6. Zinc Hydroxide Zn(OH)2
7. Copper Nitrate Cu(NO3)2
8. Barium Sulphate BaSO4
9. Sodium Carbonate Na2SO4
10. Calcium Hydrogencarbonate Ca(HCO3)2
11. Lead Iodide PbI2
12. Nickel Sulphate NiSO4
13. Ammonium Carbonate (NH4)2CO3
14. Manganese IV Oxide MnO2
15. Sodium Bromide NaBr
16. Magnesium Ethanoate Mg(CH3COO)2
17. Silver Nitrate AgNO3
18. Mercury II Chloride HgCl2
19. Magnesium Nitride Mg3N2
20. Potassium Phosphate K3PO4


What are the names of the following chemicals?

1. CuBr2 Copper II Bromide
2. K2O Potassium Oxide
3. K2Cr2O7 Potassium DiChromate (VI)
4. KNO3 Potasium Nitrate
5. AlCl3 Aluminium Chloride
6. FeCl2 Iron II Chloride
7. FeS Iron II Sulphide
8. Na2S2O3Sodium ThioSulphate
9. Al2(SO4)3 Aluminium Sulphate
10. Mg(OH)2 Magnesium Hydroxide
11. Pb(CH3CO2)2 Lead (II) Ethanoate
12. Na2Zn(OH)4 Sodium Zincate
13. Pb(NO3)2 Lead (II) Nitrate
14. KMnO4 Potassium Manganate (VII)
15. PbO2 Lead (IV) Oxide
16. Ni(NO3)2 Nickel Nitrate
17. Na2SO3 Sodium Sulphite/Sodium Sulphate (IV)
18. Ca(HCO3)2 Calcium HydrogenCarbonate
19. CuO Copper II Oxide
20. MgCO3 Magnesium Carbonate

1.1 MOLE CONCEPT AND AVOGADRO’S CONSTANT (2H) 1.2 FORMULAS (3H)

Relative molecular mass (Mr) and relative atomic mass (Ar).

Definition: The relative isotopic mass of 12C = 12

All other relative isotopic masses are measured relative to this standard and are not whole numbers e.g.

13C 13.003 19F 18.998 35Cl 34.97 37Cl 36.97

The IB requires you to use whole numbers as an approximation to the relative isotopic mass of every isotope.

The relative atomic mass (Ar) is the average value of an element’s relative isotopic masses e.g. Ar (C) = 12 * 0.9889 + 13.0033 * 0.011 = 12.0098

What is Ar (Cl) if 75.77 % is 35Cl and the rest is 37Cl?

Relative atomic masses are in your data booklet, written beneath each element’s symbol in Table 5. e.g.

The relative molecular mass (Mr) is the sum of a compound’s relative atomic masses e.g.

Mr (CO) = 12.01 + 16.00

What is Mr (CO2)?

What is Mr (Al2(CO3)3)?

Calculating the mass of one mole of a species from its formula.

Another way of saying the same thing is to use the term ‘Molar mass’

The molar mass (M) of carbon-12 atoms is 12 g mol-1

NB Molar mass has units (it is not ‘relative’)

You must specify if it refers to atoms, isotopes, molecules, etc.

EXERCISE 2:

Calculate the Relative Molecular Mass, Mr, of the following

1. Sodium Chloride

2. Copper Sulphate

3. Lead Nitrate

4. Magnesium Oxide

5. Potassium Hydroxide

6. Sulphuric Acid

7. Carbon Dioxide

8. Calcium Carbonate

9. Aluminium Sulphate

10. Sulphur Trioxide

11. Ammonium Nitrate

12. Zinc Chloride

13. Iron II Bromide

14. Iron III Iodide

15. Oxygen

16. Aluminium Zincate

17. Nitric Acid

18. Dilead II lead IV Oxide Pb3O4.

19. Magnesium Sulphate - 7 – water MgSO4.7H2O

20. Ammonium Iron II Sulphate - 6 – water (NH4)2SO4.FeSO4.6H2O

Calculate M for :-

1. Copper Carbonate

2. Potassium Dichromate

3. Magnesium Hydroxide

4. Sodium Phosphate

5. Calcium Hydrogencarbonate

6. Potassium Oxalate

7. Sodium Cyanide

8. Nitrogen Dioxide

9. Ethanol

10. Lead Chromate

11. Potassium Permanganate

12. Tin IV Chloride

13. Ethane

14. Lithium Carbonate

15. Ammonia

16. Butane

17. Sodium Chromate

18. Hydrochloric Acid

Applying the mole concept to substances.


Definition: A mole of particles contains the same number of particles as there are atoms in 12 g of carbon-12.

It turns out that there are 6.02 x 1023 particles per mole.

6.02 x 1023 mol-1 is Avogadro’s constant

Solving problems involving amount, mass and molar mass.

Maths (learn this thoroughly):

Mass = Amount x Molar mass

or

m = nM

or

Grams = Moles x Grams per mole

EXERCISE 3

1. What is the mass of 0.5 moles of calcium carbonate (CaCO3)?

2. What is the amount of 27 g of water?

3. What is the relative molecular mass of fullerene if 2/3 mole has a mass of 480 g?

4. What mass of magnesium contains the same number of atoms as there are in 4 grams of calcium?

5. Calculate the mass of iron which contains the same number of atoms as there are molecules in 16 grams of oxygen.

6. What is the mass of copper sulphate (CuSO4 ) which contains the same number of copper atoms as there are atoms in 6.5 grams of zinc?

7. How much nitrogen contains the same number of atoms as there are sulphur atoms in 3.96 grams of ammonium sulphate ([NH4]2SO4)?

8. What mass of manganese contains twice the number of atoms that there in 0.6 grams of carbon?

Empirical formula and molecular formula.

Empirical formula: the simplest expression of the proportions of the elements in a compound. The empirical formula can be obtained from the proportions of masses of each element.

Molecular formula: the numbers of atoms of each element in a molecule of a compound.

Sometimes the two formulae are the same: H2O, for example, is both the molecular and empirical formula.

Hydrogen peroxide has an empirical formula of HO but its molar mass is 34 g mol-1. Its molecular formula is H2O2

EXERCISE 4 1. Analysis of two compounds showed that they contained the following proportions of elements: A: Carbon 26.1% Oxygen 69.6% Hydrogen 4.3% B: Carbon 52.2% Oxygen 34.8% Hydrogen 13.0% Calculate the empirical formula of each compound

2. If the empirical formula of methane is CH4, and its relative molecular mass is 16, what is the molecular formula?

3. If the empirical formula of ethane is CH3, and its relative molecular mass is 30, what is the molecular formula?

4. What is the mass of carbon dioxide that is produced when 50 g of calcium carbonate decomposes?

CaCO3 → CaO + CO2

5. If 12 g of magnesium react with oxygen to produce 20 g of magnesium oxide: a. What is the formula of magnesium oxide? b. What is the equation for the reaction?

6. Determine the empirical formula and the molecular formula of the following compounds from the given information. a. 0.36 mol S are combined with 0.72 mol oxygen atoms. Mr of this compound is measured to be 64. b. 0.193 mol Fe combined with 0.2895 mol O and its molar mass is 160 g mol-1 c. 0.3285 mol Pb combined with 0.438 mol O. Mr = 685 d. 0.309 mol carbon combined with 0.618 mol H. Molar mass is 42 g mol-1 e. 0.379 mol H combined with 0.379 mol O. Mr = 34

7. A compound was shown by qualitative analysis to contain nitrogen and hydrogen as the only elements. It was found by quantitative analysis that 0.02 mol of nitrogen are combined with 0.04 mol of hydrogen. Its relative molecular mass is approximately 30. Determine its empirical formula and its molecular formula.

8. The relative molecular mass of a compound of boron and hydrogen was measured as just under 28. Every 0.25 mol of boron are combined with 0.75 mol hydrogen atoms. Find its empirical and its molecular formula.

9. Calculate the empirical formulae of the following substances whose compositions are given below: a. 5g of an oxide of magnesium which contains 3g magnesium b. 7g nitrogen combined with 16g oxygen c. 0.6g magnesium combined with 1.2g oxygen and 0.3g of carbon d. 3.5g nitrogen combined with 2g oxygen e. 4.8 g oxygen combined with 3.2 g copper and 1.4 g nitrogen f. 28.2 g of an oxide of potassium which contains 23.4 g potassium g. 0.08 mol uranium combined with 3.413 g oxygen h. 1 mol zinc combined with 32 g oxygen and 2 g hydrogen i. A chloride of lead in which 1.302 g of the compound contains 0.530 g chlorine j. Aluminium bromide which contains 2.4 g bromine in every 2.67 g of bromide

10. Determine the molecular formula of the following from the given information: a. 8 g carbon are combined with 2 g hydrogen and the molar mass is 30 g mol-1. b. 1.56 g of a hydrocarbon contains 1.44 g carbon and its relative molecular mass is 78 c. 0.2 mol nitrogen atoms are combined with every 6.4 g oxygen and the molar mass of this compound is 92 g mol-1. e. 3.55 g of an oxide of phosphorus contain 1.55 g phosphorus. Its relative molecular mass is estimated to be a little below 300.

Find the formula for each of the following substances whose percentage composition is given

11. 40% calcium, 12% carbon & 48% oxygen

12. 40% copper, 40% oxygen & sulphur

13. the oxide of copper which contains 88.9% Cu by mass

14. the hydrocarbon which contains 85.7% carbon and has a relative molecular mass of 96

15. the carbohydrate which has a molar mass of 180 g mol-1 and contains 53.33% oxygen and 6.67% hydrogen.

1.3 CHEMICAL EQUATIONS (1H)

Balancing chemical equations

Once you know the formulae of the chemicals in a reaction, you need to make a balanced chemical equation.

You cannot change the formulae of the chemicals.

You can only add coefficients to indicate how many molecules of each chemical react.

Example 1

C10H16 + Cl2 → C + HCl

This is unbalanced. Let’s balance the carbons first:

1 C10H16 + Cl2 → 10 C + HCl

Now let’s try the hydrogens:

1 C10H16 + Cl2 → 10 C + 16 HCl

Finally, time for the chlorines:

C10H16 + 8 Cl2 → 10 C + 16 HCl

Example 2

Si2H3 + O2 → SiO2 + H2O

This is unbalanced. Let’s balance the silicon first:

1 Si2H3 + O2 → 2 SiO2 + H2O

Now let’s try the hydrogens:

2 Si2H3 + O2 → 4 SiO2 + 3 H2O

Finally, time for the oxygens:

4 Si2H3 + 11 O2 → 8 SiO2 + 6 H2O

Here is a trick you can use to guide you in steps 2 and 3:

1 Si2H3 + O2 → 2 SiO2 + 3/2 H2O

Example 3

Ca10F2(PO4)6 + H2SO4 → Ca(H2PO4)2 + CaSO4 + HF

I don’t like the calcium. It appears in more than two compounds here. Next in line is fluorine:

1 Ca10F2(PO4)6 + H2SO4 → Ca(H2PO4)2 + CaSO4 + 2 HF

The phosphate and sulphate can be treated as units:

1 Ca10F2(PO4)6 + H2SO4 → 3 Ca(H2PO4)2 + CaSO4 + 2 HF

1 Ca10F2(PO4)6 + 1 H2SO4 → 3 Ca(H2PO4)2 + 1 CaSO4 + 2 HF

Note that although we have coefficients for every substance, the coefficients 1, 3 and 2 are not balanced with the coefficients 1 and 1 – so I write them in two different colours.

The hydrogens look tricky too, but it’s either them or the calcium now:

1 Ca10F2(PO4)6 + 7 H2SO4 → 3 Ca(H2PO4)2 + 7 CaSO4 + 2 HF

Better do the calcium now…

Ca10F2(PO4)6 + 7 H2SO4 → 3 Ca(H2PO4)2 + 7 CaSO4 + 2 HF

EXERCISE 5 Balance these equations: 1. Cu + O2 → CuO 2. Fe + O2 → Fe3O4 3. Mg + HCl → MgCl2 + H2 4. Al + HCl → AlCl3 + H2 5. P + O2 → P2O5 6. NaHCO3 → Na2CO3 + CO2 + H2O 7. KClO3 → KCl + O2 8. NaNO3 → NaNO2 + O2 9. Cu(NO3)2 → CuO + NO2 + O2 10. PbO + C → Pb + CO2 11. C4H8 + O2 → CO2 + H2O 12. C4H10 + O2 → CO2 + H2O 13. Na2CO3 + HCl → NaCl + H2O + CO2 14. KOH + H2SO4 → K2SO 4 + H2O 15. (NH4)2SO4 + NaOH → NH3 + Na2SO4 + H2O 16. Mg + H2O → MgO + H2 17. Na + H2O → NaOH + H2 18. Pb3O 4 + H2 → Pb + H2O 19. Fe2O3 + CO → Fe + CO2 20. Fe(OH)3 → Fe2O 3 + H2O 21. CuO + H2 → Cu + H2O 22. Zn + HCl → ZnCl2 + H2 23. KClO3 → KCl + O2 24. S8 + F2 → SF6 25. Fe + O2 → Fe2O3 26. C2H6 + O2 → CO2 + H2O

The mole ratios of any species in a chemical equation.

EXERCISE 6

1. What is the amount (unit : mole) of hydrochloric acid needed to react with 1 mol Mg and how much magnesium chloride is formed?

2. What is the amount of chlorine which will react with 4 mol Fe? How much iron III chloride is formed?

3. How much carbon dioxide can be produced by reacting 0.1 mol CuCO3 with hydrochloric acid? What is the minimum amount of acid required?

4. What is the amount of sodium hydrogencarbonate which should be heated to produce 0.2 mol Na2CO3?

5. What amount of barium sulphate can be precipitated from a solution containing 0.01 mol barium chloride? What amount of potassium sulphate will be required to react with this barium chloride? What would be the effect of adding twice the amount of potassium sulphate?

The state symbols (s), (l), (g) and (aq).

EXERCISE 7 Can you add state symbols to the equations above? Aqueous solutions and Ionic equations Many substances dissolve in water to form aqueous solutions. Ionic substances are usually soluble, separating into their component ions: Al2(SO4)3 (s)  2 Al+3(aq) + 3 SO4-2(aq) The mobility of the ions in solution means that these solutions will conduct electricity (though the solid substance will not). Covalent substances do not usually dissolve in water. If they do dissolve, the molecules remain intact: C6H12O6(s)  C6H12O6(aq) When no more solute can be dissolved in a solvent, the solution is said to be saturated.

Ionic equations describe only the ions that react, omitting other (‘spectator’) ions. AgNO3 (aq) + NaCl(aq) ® AgCl(s) + NaNO3 (aq) Each aqueous compound can be treated as a pair of ions: Ag+(aq) + NO-3 (aq) + Na+(aq) + Cl-(aq) ® AgCl(s) + Na+(aq) + NO-3 (aq) The sodium and nitrate ions do not take part in the reaction Ag+(aq) + Cl-(aq) ® AgCl(s) This treatment simplifies the equation and makes it more generally applicable. E.g. What if silver fluoride and potassium chloride solutions were mixed? When an acid and an alkali react, ionic equations can be very useful: Sodium hydroxide (NaOH) and hydrochloric acid (HCl) react to form sodium chloride and water Magnesium hydroxide (Mg(OH)2) and sulphuric acid (H2SO4) react to form magnesium sulphate (MgSO4) and water Treating Na+, Mg2+, Cl- and SO42- as spectator ions, what is the common ionic equation when a hydroxide reacts with an acid? EXERCISE 8 Write balanced equations for the following reactions. Put in the physical states in the appropriate manner and write the ionic equation as well where this is appropriate (numbers 1, 2, 5, 11, & 15). Occasionally, oxygen appears as reactant but is not in any of the named products. In these cases, assume it is converted into water. 1. Iron filings reacting with dilute hydrochloric acid to give hydrogen plus iron II chloride solution. 2. Zinc oxide powder dissolves in dilute hydrochloric acid to give zinc chloride and water. 3. In the Contact process, sulphur dioxide and oxygen combine to form sulphur trioxide in the presence of vanadium V oxide catalyst and at a temperature of 450°C. 4. When crystalline potassium nitrate [nitrate (V)] is heated, oxygen is given off and a residue of potassium nitrite [nitrate (III)] remains. 5. When chlorine is bubbled into aqueous potassium iodide, a ppt. of iodine is formed along with a solution of potassium chloride. 6. The effect of heat on dilead II lead IV oxide (Pb3O4) is to produce oxygen, leaving lead II oxide behind. 7. Baking soda, sodium hydrogen carbonate, is used in cooking and when heated it decomposes to form sodium carbonate, carbon dioxide and steam. 8. When carbon dioxide is bubbled through lime water (calcium hydroxide solution), milkiness is observed due to the formation of a ppt of calcium carbonate. 9. If carbon dioxide is allowed to continue to bubble through the solution from (8) for a long time, the ppt redissolves, forming calcium hydrogencarbonate. 10. In the blast furnace, carbon monoxide reduces iron III oxide to molten iron while being oxidised itself into carbon dioxide. 11. The chemical test for a sulphate is to add barium chloride solution to a solution of the test sample. A white ppt. of barium sulphate indicates a positive result. 12. Magnesium burns in an extremely exothermic reaction in which magnesium oxide is the product. 13. When conc. sulphuric acid (a liquid) is poured onto common salt, fumes of hydrogen chloride are observed, while sodium hydrogensulphate remains in the test tube. 14. A solution of hydrogen peroxide will decompose spontaneously, in the presence of manganese IV oxide catalyst, to liberate oxygen. 15. When solutions of ammonium chloride and sodium hydroxide were heated together, the smell of ammonia was observed. Sodium chloride was one of the other products.

1.4 MASS AND GASEOUS VOLUME RELATIONSHIPS IN CHEMICAL REACTIONS (3H)

Calculating theoretical yields from chemical equations.

EXERCISE 9

1 What is the amount of sodium nitrate (nitrate V) (NaNO3) in 17.0g ? What mass of sodium nitrite (nitrate III) will be obtained by heating this if it decomposes according to the equation :- 2 NaNO3  2 NaNO2 + O2

2. What mass of zinc oxide remains after heating 9.45g zinc nitrate? 2 Zn(NO3)2  2 ZnO + 4 NO2 + O2

3. What mass of sodium carbonate remains after heating 4.2g sodium hydrogencarbonate?

4. What mass of powdered zinc would react with 0.96 g of sulphur? What is the expected yield of zinc sulphide?

5. What will be the loss in mass on heating 6.2g copper carbonate until no further reaction takes place? CuCO3 (s)  CuO (s) + CO2 (g)

6. A solution contained 6.62g of lead nitrate. A solution of sodium chloride was added in order to precipitate lead chloride. What is the expected yield of lead chloride?

7. What is the amount of Mg contained in 4.8g magnesium? If this reacts with hydrochloric acid, what is the amount of hydrogen gas which will be produced?

8. An aqueous solution contains 12.6 g HNO3. What amount of HNO3 is this? Find the amount and the mass of potassium hydroxide which will just neutralise this. What mass of potassium nitrate could you expect as product?

9. 5.05 g of copper nitrate decomposes according to the following equation when it is heated 2 Cu(NO3)2  2 CuO + 4 NO2 + O2 (a) What mass of copper oxide is produced? (b) What amount of nitrogen dioxide is formed?

The limiting reactant and the reactant in excess: Theoretical, experimental and percentage yield.

EXERCISE 10

1. What mass of zinc will be required to react completely with 5g of copper sulphate and what mass of copper will be formed?

2. How much iron II sulphate will be required to react with 4g sodium hydroxide and what mass of iron II hydroxide will be formed?

3. 8g of calcium are dissolved in excess hydrochloric acid. How many molar masses of acid will actually react? What amount of calcium chloride can you expect? If this crystallises out of solution as CaCl2.6H2O, what is the maximum mass of crystals that can be produced?

4. A technician used 2.4g of magnesium ribbon to produce crystals of magnesium sulphate - 7 - water by reaction with dil. sulphuric acid. What should his yield (in grams) have been? If he managed to make only 16.4 g, calculate his percentage yield.

5. A portable gas stove burns butane at the rate of 116 g per hour. What mass of water will be produced after one hour? In what physical state will this water first appear? What will eventually happen to it? If the appliance is used in a confined space, state what problems or dangers might result.

6. 8.0 g of copper oxide were dissolved in dilute sulphuric acid and after suitable treatment 20 g copper II sulphate - 5 - water were obtained. What is the percentage yield?

7. Ethanol (20 cm3) was heated with an equal volume of ethanoic acid in the presence of concentrated sulphuric acid catalyst. The yield of ethyl ethanoate was 8 cm3. (a) Calculate the mass and the amount of each reagent. (b) Which of the two reagents, ethanol or ethanoic acid is the limiting reagent i.e. which is not in excess? (c) Calculate the percentage yield of ester. [ densities in g cm-3 :- ethanol 0.79; ethanoic acid 1.05; ethyl ethanoate 0.9]

8. 8.4g of sodium hydrogen carbonate are mixed with 15g of hydrochloric acid. Explain which reagent is in excess. Find the amount of carbon dioxide produced in the reaction. Would more or less carbon dioxide have been produced by heating the hydrogencarbonate?

9. On heating 4.2g of a metal carbonate, XCO 3, 0.05 mol carbon dioxide was produced. Calculate the relative atomic mass, A r, of the metal X. XCO 3  XO + CO 3

10. Bath salts (sodium carbonate crystals) (9.53g) were gently heated in a crucible in order to drive off all their water of crystallisation. 3.53g of anhydrous salt remained. Calculate the number of molecules of water of crystallisation in the sodium carbonate and hence its formula. However when 12 g of the crystals were left in a hot room, the loss in mass was only 6.80g. What can you deduce about the formula of the sodium carbonate after it had undergone efflorescense in these conditions?

Avogadro’s law of volumes of gases.

Avogadro’s law: Equal volumes of gases, at the same pressure and temperature, contain equal amounts of molecules. The law can be used to find the volumes of gases in a reaction: e.g. 1 dm3 of hydrogen will react with 1 dm3 of chlorine to give 2 dm3 of hydrogen chloride. EXERCISE 11 What volume of CO2 will be produced when 1 dm3 of methane (CH4) combines with 3 dm3 of oxygen? What volume of CO2 will be produced when 1 dm3 of ethene (C2H4) combines with 3 dm3 of oxygen?

Graphs relating to the ideal gas equation.

This section meets many criteria for Topic 11.3 Graphical techniques

EXERCISE 12

1. A sample of gas was heated while the pressure was kept constant. The changes in volume were recorded. Graph the following data:
Temperature (°C) Volume (dm3)
0 1.37
100 1.84
200 2.33
300 2.79
400 3.34
500 3.81
600 4.28

Use a scale which starts at -300 °C and 0 dm3.

Estimate the temperature required for the gas to have a zero volume.

2. Another gas sample was pressurised and the effect on its volume was recorded. The temperature was kept constant. Graph the following data:
Pressure (bar) Volume (dm3)
1 4.64
2 2.40
3 1.60
4 1.19
5 0.94
6 0.82
7 0.67

What is the relationship between pressure and volume?

3. A gas was gradually introduced to a rigid, constant temperature, vacuum-filled container, and the pressure recorded as more gas was added. Graph the following data:
Amount (mol) Pressure (bar)
0 0
1 0.500
2 0.998
3 1.510
4 1.988
5 2.517
6 3.118
7 3.441

What is the relationship between pressure and amount?

4. One mole of a gas was kept in a 1 m3 (1000 dm3) container as the temperature was varied. The effect on the pressure was recorded:
Temperature (K) Pressure (Pa)
253 2037
273 2280
293 2501
313 2615
333 2753
353 2918
373 2925

What is the relationship between pressure and temperature?

What is the gradient of the graph?

Use the gradient to estimate the temperature required for the pressure to be 101325 Pa (1 atm).

Molar volume of a gas

A mole of any gas at 298 K and 1 atmosphere pressure occupies 24 dm3. At 273 K the volume is 22.4 dm3. E.g. 2 moles of argon atoms occupy 48 dm3 0.5 moles of oxygen molecules occupy 12 dm3 What is the volume of carbon dioxide that is produced when 50 g of calcium carbonate decomposes? CaCO3 ® CaO + CO2

The relationship between temperature, pressure and volume for a fixed mass of an ideal gas.

We can summarise the behaviour of an ideal gas with this equation:

PV = nRT

P is the pressure (in Pa or N m-2)

V is the volume (m3)

n is the number of moles of the gas

R is the ideal gas constant (=8.31 J K-1 mol-1)

T is the absolute temperature (K)

You can see from this that if pressure increase, either the volume must decrease or the temperature increases. Similarly, increasing temperature causes increased volume and/or pressure.

EXERCISE 12

Use PV = nRT to calculate: a) The volume occupied by 1 mol of a gas at 25 oC (298 K) and 100000 Pa (1 bar) pressure.

b) The pressure required to make 5 mol of gas occupy 50 dm3 (50 x 10-3 m3) at 35 oC.

c) The number of moles of gas which occupy 25 dm3 at 85 oC and 1.05 bar.

d) The temperature of a 3 mol gas sample which has a volume of 18 dm3 at 1 atm (1.013 bar) pressure.

If we change the conditions for a given sample of gas, we can simplify the equation considerably. Call the initial pressure, temperature and volume P1, T1 and V1, and the values after the conditions have changed are called P2, T2 and V2. The amount of gas, n, and the constant, R, are the same in both cases. This gives us the formula:

= P1*V1 / T1 = P2*V2 / T2

The ‘1’ and ‘2’ refer to the volume (V) of the gas under different conditions of Pressure (P) and Absolute Temperature (T - measured in kelvins) Helpfully, the pressure and volume do not now have to measured in Pa and m3. Any units are suitable, so long as the same units are used for P1and P2, and for T1 and T2.

EXERCISE 13

1. Use the simplified equation (and answers to the previous exercise) to calculate:

a) The volume occupied by 1 mol of a gas at 0 oC and 100000 Pa (1 bar) pressure.

b) The pressure required to make 5 mol of gas occupy 40 dm3 (50 x 10-3 m3) at 35 oC.

c) The temperature of a 3 mol gas sample which has a volume of 25 dm3 at 1 atm (1.013 bar) pressure.

d) If a sample of gas which occupies 26.25 dm3 at 120.8 oC and 1.10 bar could be the same as a sample which occupies 25 dm3 at 85 oC and 1.05 bar.

2. If 1 dm3 of gas is warmed from 298 to 745 K, while the pressure is kept constant at 1 atm, what is its new volume?

3. What pressure is now required to pressurise the hot gas until it reaches its original volume?

1.5 SOLUTIONS

Solute, solvent, solution and concentration

Concentration (c) is measured as the quantity of solute per unit volume (usually per dm3 i.e. dm-3) of solution (not solvent). Remember that 1 dm3 = 1000 cm3 The solute quantity can be measured as mass, so the units are g dm-3. cm = m/v mass concentration = mass / volume The solute quantity can be measured as amount, so the units are mol dm-3. cn = n/v molar concentration = amount / volume The molar concentration of a substance is often written in the shorthand form [substance]. E.g. Instead of writing ‘The molar concentration of NaCl’ we can write [NaCl].

EXERCISE 14

1) Write down all the possible mathematical expressions which might be needed when doing calculations based on volumetric analysis (titrations).

2) What is the mass concentration if 5 g of NaCl are dissolved in 500 cm3 of solution?

3) What is the amount of 5 g of NaCl?

4) What is the molar concentration if 5 g of NaCl are dissolved in 500 cm3 of solution?

5) 25 cm3 of hydrochloric acid (0.12 mol dm-3) were just neutralised by 28.4 cm3 of sodium hydroxide solution. Calculate the concentration of the base.

6) 23.2 cm3 of hydrochloric acid were required to cause the formation of the very pale grey colour - almost colourless - of screened methyl orange indicator in 25.0 cm3 of potassium hydroxide solution. Determine the concentration of the acid given that the potassium hydroxide was made by dissolving 1.372 g in 250.0 cm3 of solution.

7) A sample of lithium hydroxide was weighed as 0.62 g. It was dissolved in water & made up to 250.0 cm3. 25.00 cm3 aliquots were titrated and 21.25 cm3 of standard hydrochloric acid (0.100 mol dm-3) were required. The lithium hydroxide is thought to be contaminated with lithium chloride. Calculate the mass of lithium hydroxide in the sample and hence its percentage purity.

8) Butanedioic acid is a dibasic acid (diprotic acid) of molecular formula C4H6O4. 1.0073 g were weighed, dissolved in water and the solution made up to 250 cm3. 25 cm3 portions required 23.95 cm3 of potassium hydroxide solution to cause the colour change of a suitable indicator. Calculate the concentration of the alkali.

a) What amount of butanedioic acid was used (how many moles)?

b) What amount was used in each titration?

c) What amount (mol) of potassium hydroxide was present in each titration?

d) What is the concentration of potassium hydroxide?

9) A technician was asked to analyse a solution of commercial caustic soda for its sodium hydroxide & sodium carbonate content. She did this by titrating a 25.00 cm3 portion with hydrochloric acid solution (0.100 mol dm-3.) using firstly phenolphthalein and then, as part of the same titration, by adding methyl orange.

Results obtained were 16.90 cm3 of acid to bring about the colour change of the phenolphthalein and a total end point of 24.55 cm3.

At the first colour change (phenolphthalein goes pink to colourless), the reactions taking place are:

OH- + H+  H2O & also CO3-2 + H+  HCO3-2.

At the second colour change (methyl orange turns green to red), the reaction taking place is

HCO3-2 + H+  CO2 + H2O

Thus the first part of the titration relates to the concentration of hydroxide plus carbonate. The second part refers to the concentration of the carbonate (in its hydrogencarbonate form) only.

a) Calculate the number of moles of acid used in the first part and thus the total number of moles of hydroxide plus carbonate in the 25.00 cm3 portion.

b) Calculate the volume and hence the number of moles of acid used in the second part of the titration and thus the number of moles of hydrogencarbonate (and thus carbonate).

c) From a) & b) calculate the number of moles of hydroxide and of carbonate in the 25.00 cm3 portion. From these results calculate the concentrations of the sodium hydroxide & sodium carbonate in the solution. Give your answer in each case in mol dm-3 & also in g dm-3.

10) 1.483 g of the mineral Dolomite were added to excess hydrochloric acid (50 cm3, 1.0 mol dm-3). After reaction was complete, the solution was filtered and made up to 250 cm3. 25 cm3 portions of this solution containing unreacted acid were titrated against 0.1 mol dm-3 KOH when a mean titre of 26.3 cm3 was obtained. Assuming that Dolomite is essentially magnesium carbonate plus insoluble silica, calculate its percentage composition.

a) What amount of potassium hydroxide was in the 26.3 cm3?

b) What amount of hydrochloric acid would have reacted with this?

c) What amount of hydrocloric acid was in the 250 cm3 solution?

d) What amount of acid was taken at the start?

e) What amount of acid reacted with the Dolomite?

f) Calculate the amount and hence the mass of magnesium carbonate which would have reacted with the hydrochloric acid.

g) Calculate the percentage by mass of magnesium carbonate in Dolomite.

Chemical Reactions

The chemical reaction is a process of chemical change between reactant substances (reactants) are transformed into substances the reaction products (products). In a chemical reaction, a substance turns into one or more other substances, a new species.

When you learn about the elements you already know in advance about the chemical symbols of the element. Well, to facilitate the study of chemical reactions matter should first understand how the writing of chemical reactions.

Example: To write a chemical reaction that occurs when chunks of limestone that is inserted into the water and then the water gets hot.To write the reaction between calcium oxide CaO (s) with water H2O (l) is as follows:



The results of the chemical reaction process is Ca (OH) or calcium hydroxide soluble in water and if left in place it will appear sediment / white solids in the bottom of the vessel.

Explanation of symbols in a chemical reaction:



Reaction Coefficient

In writing a chemical reaction we must also consider the number of digits to the left of the reagent (reactant) and the reaction (the product). The number is called the coefficient that indicates the number of each atom that play a role in the reaction. The mass of a substance before and after the reaction did not change during a chemical reaction takes place.

Example:


Solution of lead (II) nitrate is reacted with potassium iodide are dissolved in water to give a solid lead (II) iodide are colored yellow and liquid potassium nitrate.

In chemical reactions the number of atoms that make up the substance nothing is lost, only rearranged, so for the reaction as mentioned above can be described as follows:



How to determine the coefficient of the reaction of a chemical reaction?

If given the example of magnesium ribbon burned to produce a solid form of magnesium oxide (white)

Phase I
Determine the position of the reagent (reactant) to the left and the products of the reaction on the right of the arrow.


Pereaksinya is Mg (Magnesium) in the form of solid / solid and O2 (Oxygen) in gaseous form; remember the burning process needs oxygen. Reaction products (products) in the form of MgO (magnesium oxide).

Phase II

Balance the atoms in the equation. From the reaction equation is the number of magnesium atoms of the reactants is equal to the amount of magnesium atom reaction products (products). Well for the oxygen atom has not been the same. Yet oxygen is a diatomic atom, ie each molecule contains two atoms of oxygen.



Phase III

If the chemical formula is correct but has not been balanced once seen the number of atoms then the next step is to equalize the coefficients in front of the substance of the reactants or products.
If the reaction of sample we add the number 2 in front of the substance of the reaction (MgO) to equalize the amount of oxygen the chemical reaction becomes:



However, the amount of Mg on the left are still numbered 1, then the number 2 when added in front of the reactant Mg chemical reactions can be written as:



can now be seen in the table:



These reactions are called equilibrium where the number of atoms of reactants and products (the reaction) is the same and is called balanced equation.

The Miracle In The Atom

In the world in which we live, mankind is caught up in a continuous search for the answers to many questions like "what?", "how?" and "in what way?", and can make but little headway in answering them. It is unlikely for man to make his way to the truth unless he asks himself the question "why?" about the extraordinary order and balance with which he interacts.

In this book, we will deal with the subject of "the atom", the groundwork of every animate and inanimate thing. After seeing what occurs and in what way it occurs with regards to the atom, we will seek the answers to the question "why?" The answer to this question will take us to the truth we pursue.

Since the first half of the 19th century, many scientists worked day and night to reveal the secrets of the atom. These studies that uncovered the form, motion, structure and other properties of the atom shattered the very grounds of classical physics that assumed matter to be an entity without any beginning or end, and laid the foundation for modern physics. They also produced many questions.

Many physicists, looking for answers to these questions, finally agreed that there is perfect order, unerring balance and perfect design in the atom, as in everything else in the universe.

This truth is revealed in the Qur'an sent down by Allah fourteen centuries ago. As made clear in the verses of the Qur'an, the whole universe works in perfect order because the earth, the sky and everything in between is created by Allah, Who has infinite power and wisdom.

Everything created by Allah has extraordinary excellence and runs within a flawless order. What comes as a real surprise is some peoples unrelenting insensitivity towards the numerous miracles they encounter, see, hear, and know – including their own bodies – and their negligence about the reason "why" these extraordinary details are presented to them.

Though dwelling on a scientific subject, the purpose of "The Miracle in the Atom" is different from that of conventional scientific books. This book deals with the "atom", unique in being the building block of both animate and inanimate objects, with the questions "what?", "how?" and "in what way?", thereby opening the door to the answer of the question "why?" Once beyond this door, the superiority of the wisdom and knowledge of Allah, and His creation are revealed for all to see:

Allah, there is no God but Him, the Living, the Self-Sustaining. He is not subject to drowsiness or sleep. Everything in the heavens and the earth belongs to Him. Who can intercede with Him except by His permission? He knows what is before them and what is behind them but they cannot grasp any of His knowledge save what He wills. His Footstool encompasses the heavens and the earth and their preservation does not tire Him. (Surat al-Baqara: 255)

ATOM CREATION PERFECTION

STRUCTURE OF ATOM

Air, water, mountains, animals, plants, our bodies, we sit on chairs, in short everything we see, we conjecture, and we taste, ranging from the heaviest to the lightest is formed of atoms. Each page of the book you are holding consists of billions of atoms. Atoms are particles so small that not likely to be seen even using the most advanced microscopes. The diameter of an atom is only one millionth of a millimeter.

It is impossible for humans to imagine this size. Therefore, let us try to explain with an example:

Imagine you are holding a lock. No doubt, you could not see the atoms in this key. If you still want to see it, then you have to enlarge this key resembles the earth. Once you lock the size of the earth, then every atom in it the size of cherries. 13

Let us consider another example in order to understand the smallness of this, and how all places and all things are filled with atoms:

Let's say we want to count all the atoms in a grain of salt, and suppose that we can count one billion atoms per second. Although we are very nimble, it will take more than five hundred years to count the number of atoms in a grain of salt. 14
Then, there inside a small structure?

Although very small, in the atom there is a flawless system, unique, and complex in its sophistication comparable to the system that we see in the universe in general.

Each atom is made up of a core and a number of electrons moving in orbit at great distances from the nucleus. At the core there are other particles called protons and neutrons.

In this chapter, we will observe the atomic structure of the incredible which is the basis of all living and dead, and seeing how atoms combine to form molecules and eventually the material.

Contained in the core strengths

The nucleus is located right in the center of the atom and consists of a number of protons and neutrons depending on the properties of these atoms. The radius of the nucleus is about a thousandth of the radius of the atom. To express it in numbers, the radius of an atom is 10-8 (0.00000001) cm, and the radius of the core is 10-12 (0.000000000001) cm. Therefore, the core volume is equal to one ten-billionth of the volume per atom.

Because we can not imagine the magnitude (or rather small) numbers, let's take the example of the cherry. Let's look inside the atomic nucleus that has us imagine the size of cherries when the key in your hand for the earth. Even at that scale like that, it is still impossible for us to see the core, which is still very, very small. If we really want to see it, then we must change the scale again. Cherry representing atoms, should be enlarged again become a giant ball with a diameter of 200 meters. Even in a scale that is difficult to believe this too, the core of the atoms no bigger than a grain of dust. 15

As small as that, so when we compare the core diameter and 10-13 cm diameter of an atom is 10-8 cm, we arrive at the following result: if we assume that the atom was a ball, and if we want to meet with the core of this sphere, then we would require 1015 (1 billion. 000 000) core to fill it. 1

Yet there is one thing more surprising: although the size is one ten-billionth the size of the atom, the mass of the core includes an atomic mass of 99.95%. How could something that occupied almost the entire mass, on the other hand, almost no space?

The reason is that includes the mass of the atom density is not spread evenly throughout the atom. Almost the entire mass of atoms accumulated in the nucleus. Say, you have a house of 10 billion square meters, and you have to put all the furniture in the house to a room of one square meter. Can you do it? Of course not.

but the nucleus of the atom can do this thanks to the great styles that are different from other styles in the universe. This style is the strong nuclear force, one of the four fundamental forces in the universe that we mentioned in previous chapters.


We have examined that this style, the most powerful force in nature, keeping the nucleus remains intact and no decomposition occurs. All protons in the nucleus has a positive charge and they repel because the electromagnetic force. However, because of the strong nuclear force is one hundred times stronger than the repulsive force of protons, the electromagnetic force becomes ineffective, and the protons remain in orbit.

In conclusion, there are two powerful forces that interact in the atom is too small to see. The core may remain intact thanks to the value of these styles appropriately.

If we compare the size of atoms and the number of atoms in the universe, impossible to ignore that there is a balance and exceptional design that is at work. It is obvious that the fundamental forces in the universe has been specially created with great wisdom and power. For those who do not want to believe, can only state that all these came into being because of "coincidences". However, scientifically probability calculations have suggested that the balance in the universe formed by "chance" chances are "0" All this is clear evidence of the existence of God and the perfection of His creation.

My Lord encompasses all things in knowledge. So if you can not take lessons. (Surat al-An `am, 6:80)

Space in the Atom

As mentioned previously, the bulk of the atoms is space. This raises the same question on everyone: why is there a space as it is? Let us think. In a simple sentence, the atom consists of a core, surrounded by electrons. No there is nothing else between the nucleus and the electrons. Microscopic distance "where there is not anything", actually very large in the atomic scale. We can model this scale is as follows: If a marble is one centimeter in diameter represents the electron closest to the core, the core will be located one kilometer away from the marbles are .17 We can cite the example below to clarify the comparative proficiency level:

There is a space lying between the basic particles. When I think of the proton of an oxygen nucleus as the "head of a pin" located on the table in front of me, then the electrons moving around it to form a circle, would pass through the Netherlands, Germany, and Spain (The writer is living in France). Therefore, if all the atoms that make up my body came together so close to touch each other, you will not be able to see me again. You really will never be able to see me with the naked eye. I will be as small as dust particles are size of a several thousand millimeters .18


At this point, we realize that there are similarities between the largest and the smallest spaces that we know in the universe. When we turn our eyes to the stars, once again we see a void similar to that of the atom. There are billions of miles either void between stars and between galaxies. However, in both of these voids, an order that is beyond human understanding is evident.

Inside the Nucleus: Protons and Neutrons

Until 1932, thought that the nucleus consists of protons and electrons. Later found that it is not electrons but neutrons in the nucleus besides the protons. (A famous scientist, Chadwick, proving the existence of neutrons in the nucleus in 1932 and he received the Nobel Prize for this discovery). Humans introduced to the real atomic structure only recently.

Have Mentioned before how small is the nucleus of the atom. Proton size that can fit into the atomic nucleus is 10-15 m.

You might think that such a small particle would not be meaningful to a person's life. However, the particles are very small that humans can not imagine it forms the basis of everything that you see around you.

Source of diversity in the Universe

There are 109 elements that have been identified to date. The universe, our earth, and all things animate and inanimate, was formed with the preparation of 109 elements in various combinations. Until now we have seen that all elements are made of atoms that are similar to each other, while the atom is also made of the same particles. So, if all the atoms that make up the elements are made of particles of the same, whether the elements that make it different from each other and cause the formation of a substance that is very diverse?

Is the number of protons in the nucleus of atoms that principally differentiates the elements from one another. There is one proton in the hydrogen atom, the lightest element, two protons in the helium atom, the second lightest element, 79 protons in a gold atom, 8 protons in the atoms of oxygen, and 26 protons in the atoms of iron. That distinguish gold from iron, and iron from oxygen is just different numbers of protons in the atoms. The air we breathe, our bodies, plants and animals, the planets in space, living things and inanimate, bitter and sweet, solid and liquid, and so on ... everything is made ​​up of protons, neutrons, and electrons.

The Borderline of Physical Existence: the Quarks

Until 20 years ago, believed that the smallest particles that make up atoms are protons and neutrons. But recently, it was found that there is a much smaller particles inside the atoms that make up the particles mentioned above.

This discovery led to development of a branch of physics called "Particle Physics" investigating "sub-particles" in the atoms and their movements. Particle physics research revealed that protons and neutrons that make up atoms are actually formed of sub-particles called quarks.

Research in the field of "particle physics" is underway to solve the secret world of subatomic particles. However, even with all the intelligence, awareness and knowledge of man, recently we only managed to find the basic particles that make up everything, including ourselves. Furthermore, the more we observe these particles, the more detailed the subject, and us in the lurch by the boundary dimensions 10-18 m of the quarks. So, what lies beyond this limit?

Today, the scientists had put forward various hypotheses about this subject, but as mentioned above, this limit is the farthest point that we can achieve in the material universe. Everything beyond this point can only be expressed as energy rather than matter. The important thing is that man finds, in a location that can only be found after all the technological means at his disposal - the balance outstanding and the laws of physics that has been running like clockwork. Furthermore, this location is inside the atoms, which are the building blocks of all matter in the universe, including living creatures.

Humans are just beginning to realize the perfect mechanism to function without fail in the organs and systems in his own body. Discovery of the mechanisms of the cells forming these structures are only a few decades ago. Creation that looks great on the atoms of cells, the protons and neutrons in atoms, and quarks in the particles, so perfect that it surprised everyone, regardless of whether he believes or not. The basic point to consider here is that all these perfect mechanisms run regularly every second throughout the human life, without interference, and utterly beyond his control. This fact is a proof for every person who uses his conscience and his knowledge that all was created and governed by God, Owner of the supreme power and knowledge.

"Everything in heaven and on earth has always ask Him. Every time in rushing him. Which favors of your Lord will you Which you deny?" (Surat AR-Rah-man, 55: 29-30)

Another aspect of Atoms: Electrons

Electrons are particles that rotate and evolve / revolves around an atomic nucleus as well as the earth rotates on its axis and also rotates around the sun. This rotation, such rotation of the planet, it runs constantly and very organized in pathways, which we call the orbit. However, comparison of the size of the earth and the sun is very different from the atomic scale. To make a comparison between the size of the electron and the size of the earth, if we enlarge an atom of earth, then the electrons will only apples for .19


Dozens of electrons that evolved in the area is so small that no visible while utilizing the most advanced microscopes create a very complex traffic inside the atom. The most amazing thing here is that these electrons surrounding the nucleus like a shield of electric charge, never had a small accident. In fact, any small accident inside the atom can lead to disaster for the atom. But such an accident never happened. The whole operation runs smoothly. The electrons that surround the core with a shock speed of 1,000 km / sec, never collide with each other. It is amazing that these electrons, which are not different from each other, rotating in its own orbit, and this is clearly the result of a "conscious creation". If they have different masses and speeds, perhaps natural that they have different orbits around the nucleus. For example, the order of the planets in our solar system follows this logic. The planets that have masses and speeds different from each other by themselves have different orbits around the sun. But the case of electrons in the atom is entirely different from these planets. All electrons are both correct but have different orbits around the nucleus: How were they to follow this path accurately, how they can not collide with each other even though they are so small and move at incredible speeds? This question brings us to a single conclusion: the only truth that we see in a unique order and balance of this complex is perfect creation by God.

"He is Allah the Creator, The Hold, The Shaping Arts, The Names Have The Most Good. Remix Him what is in the heavens and on earth. And He is the Mighty, Wise." (Surat al-Hashr, 59:24)

Electrons are tiny particles, measuring nearly half-thousand measure neutrons and protons. An atom has a number of electrons and protons are equal and each negatively charged electrons are equivalent to positive charge contained in each proton. The total positive charge on the nucleus and the total negative charge on the electron cancel each other out and become neutral atoms.

The electric charge makes the electrons obey the laws of physics. One of the laws of physics is "the same electrical charge repel each other and opposite charges attract each other".

First, under normal conditions, the electrons, all negatively charged, repel each other should follow this law and get away from the core. However, this does not happen. When electrons are detached from the core, then the universe would consist of protons, neutrons and electrons that roam freely in empty space. Second, the positively charged nucleus that should attract the electrons are negatively charged, so electrons will be attached to the core. In this case, the nucleus would attract all the electrons and the atom would implode.

However, none of this happens. Remarkable speed electrons mentioned above (1,000 km / sec), the force repelling the electrons released by the fellow, and the force of attraction between the nucleus and electrons, are the values ​​that are so precise that the three factors opposing balance each other perfectly. As a result, the system is extraordinary in the atom runs without failure. Even if the value of one of the forces acting on the atom more or less than it should, the atoms would not exist.

In addition to these factors, if there are no nuclear forces binding protons and neutrons in the nucleus, protons having equal charges could not even come close to each other, let alone binds in the nucleus. In the same way, the neutrons will not be attached to the core. As a result, there will be no nucleus and therefore, there is no atom.

All calculations are indications that an atom is not idle but acts under the perfect control of Allah. If not, inevitable that the universe we live in is doomed to extinction before it begins. This process will turn around at the beginning and the universe will not be formed. But God, the Creator of all things, the Almighty and the Almighty, establish a very precise balance in the atom as he sets out all of the balance in the universe, for which the atoms continue to exist in perfect order.

Scientists have been giving their best efforts for years to uncover the secrets of the balance set by God, and so far only managed to give a name to the symptoms observed as "the electromagnetic force," "strong nuclear force", "weak nuclear force" , and "mass attraction force" ... But, as mentioned in the introduction to this book, no one thought to the question "Why?" Why are these forces operate at a certain intensity under certain rules? Why is the area subject to these forces, the rules that they obey, and intensity of these forces, a harmony that is so great? "

Scientists were desperate in the face of all these questions because they can do is guess at the order in which events occur. Their research, however, gave rise to an indisputable fact. Every point in the universe shows the interference of intelligence and will of the owner, who does not let a single atom was unemployed. There is a single force that keeps all of these styles in harmony, and that is Allah, Who holds all power and authority. God manifest His power wherever and whenever He wills He wills. The whole universe, from the smallest atom to the galaxy of endless able to continue its existence only because God's will and care.


Indeed the exchange of the night and day, and on what
God created the heavens and on earth, actually there are signs
(His power) for those who fear Him.
(Qur'an, 10:6)



In the Qur'an, Allah states that there is no power but Him and He announces the punishment for those who, because of their ignorance, assume that helpless creature (living or dead) which Allah has created independent power and strength from Him, and to attribute characteristics of the divine in them.

"And if ever the people who do wrong at the time when they see the punishment (on the day), that power belongs to Allah, and that Allah is severe in punishment (they would regret it)." (Surat Al - baqarah, 2: 165)

So far, no scientist is able to explain the cause and source of the forces in the atom and therefore in the universe anyway, and why certain styles of play at certain moments. Conducted by science is to make observations, measure and fabricate "names" for their findings.

PARTICLE-PARTICLE accelerated

Accelerators and impactor

Assessment of the particles that are the building blocks of matter is possible by investigating the particles millions of times smaller than atoms.

A study of microscopic particles can only be done by using particle physics experimental equipment is very complex and large. In such a complicated experiment that can only be done with extensive computer use.

High-energy particle physics is the science that studies the building blocks of matter and the interactions between them. Recent experiments carried out with the aid of sophisticated new technologies allow us to quickly expand our knowledge about the composition of matter.

Research on the physics of particle acceleration in the laboratory particle diameter for miles. Inside the accelerator, the charged particles - mostly protons and electrons - accelerated to very high velocity through the electromagnetic field and directed at the cloud chamber. The particles are accelerated and then collided with a target made permanent or with others. The particles are broken as a result of these collisions will be tested with various detector systems.

Accelerator and detector technology, the rapidly increasing sophistication since 1950, making possible high-energy collisions. The study of these collisions by the detector system further pave the way for the discovery that protons and neutrons, which is known as the base material, has a sub-structure consisting of particles, called quarks. Measurements were taken at a high energy level provide opportunities for scientists to study the composition of matter at distances as small as one hundredth of the radius of the proton. Accelerator laboratory found only in a few centers in the world for the establishment and operation are very expensive. Most important is the CERN (Geneva), DESY (Hamburg), Fermilab, FNAL (Chicago) and SLC (California). The high-energy physicists to follow this experimental study at these centers in large groups and learn the secrets of the atom. Among these labs, SLC diameter 3 km and 27 km CERN. However, the winner in a competition of this size is a U.S. project, the SSC is being built in central Texas, United States, with a diameter of about 85 km. Equipment costs increased in proportion to the size (for the SSC, the figure is close to 6 billion dollars) 20.

"Naming" as it is considered a major discovery in the world of science. Though scientists do not attempt to establish a new balance in the universe or build a new system, but just an attempt to understand and decipher the secret of a real balance in the cosmos. What they do is simply observe one of the wonders of countless of God's creation in the universe and renamed it. The scientists who detected the system or structure created by God were given various scientific prizes, respected and admired. In this case, that should really be respected, without any doubt, Allah, the Most Gracious, the Most Merciful, who created the system from nothing into existence, complete with a balance of highly complex and constantly creating incredible miracle.

"Surely, in exchange of the night and day, and on what God created the heavens and the earth, actually there are signs (of his power) for those who fear Him." (Surah Yunus, 10: 6)

Electron Orbit

Dozens of electrons, the spinning and orbiting in a region not observed even by the most sophisticated microscopes, create an extremely complex traffic inside the atom as we mentioned earlier. But traffic is so irregular, is unparalleled by most systematic city traffic. Electrons never collide with each other, because each electron has its own orbit and the orbits are not identical.

There are seven layers of electrons around the atomic nucleus. The number of electrons that never changed in seven skin is determined by a mathematical formula: 2N2. The maximum number of electrons that may exist in each skin has been determined by this formula (n indicates the number of electron shells).

ELECTRON LIFE HELPING PEOPLE

Electricity is one of the most important part of our lives. It seems we can not do anything without him. Our lives are tied to electricity when we are eating, watching TV, traveling from one place to another or cleaning the house. We pushed the button and everything around us becomes light. You press another button, and all electrical appliances to work. Form of electricity that we use every time is called electric current. What makes this happen is the flow of electrons we are talking about since the beginning of this book. Electricity is the flow which is formed from the movement of charged electrons and negatively charged ions. Equipment such as televisions and refrigerators in every day use electricity needs of 1-2 Ampere. So, what does this number? A current of 1 Ampere / sec means the transmission 6 billion times a billion electrons per second from a certain area. This is a million times greater than for a bolt of lightning.

That an infinite number of electron shells of atoms making up the universe loyal to the same number by following the formula 2N2, showing regularity. That there is no chaos occurs inside the atom, although the electrons move with incredible speed, it also shows unique order. This is the same regularity can not be considered as a coincidence. The only explanation for the existence of this order is that God created everything as a manifestation of His power in order and harmony as the Koran. God refers to His created order in the verses of the Qur'an:

"Allah has appointed a measure for all things." (Surah Ath-Thaalaq, 65: 3)

"He has created everything, and he determined it most exactly." (Surat al-Furqaan, 25: 2)

"And all things in His sight size. The Knower of the Unseen and the visible; again Almighty Most High." (Surat ar-R'ad, 14: 8-9)

"And We have spread out the earth and make him the mountains that we everything grow according to size." (Surat al-Hijr, 15: 19)

"The sun and the moon follow courses (exactly) computed." (Surat Ar-Rahman, 55: 5)

"And God raised the heavens, and He put the Balance (justice)" (Surah Ar-Rahman, 55: 7)

As mentioned verse, God, King of the whole world, He Who created all things in proportion, size, and perfect regularity. The proportion and size of these cover the whole universe, from the smallest subatomic particles, until the giant objects in space: the solar system, galaxies, and everything in between them. Strength, knowledge, and artistic taste of God's vast and limitless is what generates all that. God introduced His nature to mankind in size, regularity, and perfect balance on the creature and the system that created him. He showed endless strength before our eyes. This is the truth that human beings should be addressed by the research and its scientific calculations.

Waves or Particles?

When electrons were first discovered, these particles are considered the same as protons and neutrons are found in the nucleus. However, in subsequent experiments, it was found that they exhibit wave characteristics like light particles, namely photons. Then, Quantum Physics conclude that each particle is also a wave form with a certain frequency.

It is known that light propagates in the same way as waves on the surface of the water when a stone thrown into the lake. However, sometimes light and matter particles have the characteristics observed in the form of sporadic and periodic pulses like drops of rain that falls from the window sills. This same dichotomy occurs also on the electron, which raises considerable doubt in the scientific world. Explanation Richard P. Feynman was a famous professor of Theoretical Physics alleviate this confusion:

Now we know how the behavior of electrons and light. But how do I call? If I say they behave like particles I give the wrong impression; so if I say they behave like waves. They behave in their unique way, which technically can be called a quantum mechanical way. They exhibit behaviors that you've never seen before .... An atom does not behave like a load-dependent spring and swinging. Also unlike a mini model of the solar system with little planets revolved around its orbit. Nor does it seem like a mist or cloud surrounding the nucleus. Atoms behave unlike anything you've ever seen before. But at least there is simplification. Electrons behave in this case with exactly the same way as photons; both are odd, but with the same strangeness. So it takes imagination to appreciate their behavior, because we will describe something different from anything you ever knew. 21

SIGNS OF AL-QURAN

When studying the electron shell, we must also consider that explain this verse in the Qur'an. There are seven layers of electrons around the atomic nucleus. In every shell there are certain number of electrons. Could it be a statement of "seven heavens" is used in the Quran to describe the layers that make up the sky, intended also as an electron shells as if the heavens of the atom? (Surat al-Mulk, 67:3)

This number never changes. Never to 6 or 8. Here, the most miraculous is that the number seven electron shells is in accordance with this paragraph.



Because scientists have never been able to explain the behavior of electrons, as the solution they gave him a new name: "Movement of Quantum Mechanics". Let us quote again the words of Professor Feynman with these words express the extraordinary nature of the electron and the awe he felt:

Do not keep saying to yourself, if you still can avoid it, "how could such behavior?" because you will "get lost", came to an impasse that no one made it out. No one knows how could such behavior .22

However, the deadlock is called Feynman actually not the case. The reason why some people do not find a way out of this dilemma is that even if there is real evidence, they can not accept that the system and the balance outstanding is held by the Almighty Creator. The situation is very clear: God created the universe, complete with exceptional balance and made into existence without any previous example. The answer to the question of scientists' how could such behavior? " that can never be solved or understood, lies in the fact that God is the Creator of all things, and that everything exists only because of his command "Be!"

"God created the heavens and the earth, and if He wills (to create) something, then (enough) He just said to him: 'Be'. And it is." (Surat al-Baqara, 2: 117)

Colorful World Gate Opened by Electrons

Have you ever thought how to live in a world without color? Just imagine if your body is, the people around you, sea, sky, trees, flowers, in short, all black. You do not want to live in a world like that, right?

What makes this world colorful? How the colors that make the world appear so beautiful?

Certain characteristics that exist in the material allows us to capture the colored object. Color was formed as a natural result of certain movements of electrons in the atom. You may be thinking "What does the movement of electrons with the color?". Let us explain this relationship

Electrons evolved only in electron shells. We just mention that there are seven electron shells. Each electron shell has a certain energy level, which varies depending on the distance of the skin to the core. The closer the electron shell with the core, the smaller the energy of electrons, and the farther the distance to the nucleus, the greater the energy of electrons.

Each electron shell has a "sub-skin (sub-shells)", in which the electrons from the skin as it moves constantly.

One needs to receive external energy electrons that can move from one skin to another skin. This energy source called "photons".

In simplest terms, the photons are "particles of light". Every star in this universe is a source photons. Photon sources are most important to our world is, of course, the sun. Photon spread to all corners of the sky from the sun with a speed of 300,000 miles per second.

When photons from the sun it arrives on Earth and an object hit the atoms in the earth, sometimes atomic electrons begin to move. If the electrons which can move with the help of this energy to the skin jump higher energy and return to his native skin, it will emit photons, which form a color that will caught your eye. Any process that has been summarized in a few sentences above has been going on since the beginning of creation without failure. Each step runs under intense planning and follow rules. If one part of the interaction between electrons and photons do not work, the universe will be dark and without color.

Let us step back sort of work that must happen to follow the plan and regularly to the formation of colored universe, rather than dark.

# The light coming from the sun to the earth in the form of photon particles diffuse. Photon particles are spread throughout the earth and collide with atoms of matter.

# Photons can not move much in the atom. They ran down the electrons orbiting the nucleus.

# Electrons absorb (absorb) photons that crashed into him.

# When the electrons take energy from the photons are absorbed before, he jumped into another skin that has a higher energy level.

# These electrons try to return to her old house.

# If returning to its original skin, it emits a photon of energy load.

# Photons emitted by these electrons determines the color of an object.

Seventy percent of light that reaches our planet from the sun is very appropriate portion to the survival of life on earth.

To summarize, the color of an object consisting of a mixture of particles of light that is absorbed and then emitted by this object, and reaches our eyes. The color of objects that do not emit its own light but reflect the light it receives from the sun depends on two things: the light it receives and the changes he has made in this light. When an object is illuminated with white light appears "red", this is because the object absorbs a large portion of the mixture which reached him from the sun and emits only red only. The definition of "absorbing" is as follows:

As mentioned previously, each having sub-skin leather and electrons move between the sub-sub-skin leather. Each skin has a certain energy level and electrons carry as much energy as the energy levels allowed by the skin that they pivot around. Skin that is more distant from the core has a greater energy. When one room for one electron becomes available at a higher skin, electron suddenly disappeared, and then reappear in the subshell with a higher energy level. But, so electrons can do this, it must increase its energy to the level requested by the skin of the goal. Electrons will increase its energy by absorbing (swallowing) photon particles from the sun.

We can make the situation more clearly with some examples. Let us consider the Morpho butterfly. Pigment on the butterflies absorb all sunlight and re-emit only the blue. When particles of light to the reflected color of the eye reaches the retina, they are converted into electrical signals by the cone cells in the retina in a way that captured the color blue and then sent to the brain. Finally, the blue color is formed in the brain.

This means that the color of an object depends on the character of the light emitted from the light source and how much of this light re-emitted by the object. For example, the color of a dress is not the same when viewed under sunlight and under the store lights. If an object is considered black by our brains, it means that this object absorbs all the light from the sun and nothing is reflected. Similarly, if the object reflects all the light from the sun and do not absorb it at all, then the brain we catch the white color of the object. In this case, the things we need to look are as follows:

# The color of an object depends on the properties of light emitted by light sources.

# The color of an object depends on the reaction of electron-electron molecule in its structure, for example, what light will be absorbed by these electrons and the light of what is not absorbed.

# The color of an object depends on how our brain to capture photons on the retina.

Here, let us pause and think again.

Electrons that evolved with amazing speed around the nucleus, which is a material that is too small to be seen the eyes, suddenly disappeared from her skin and jump to another place called the sub-skin. Also needed space on the sub-skin to leap. Electrons gain energy needed during the process by absorbing photons. Then he went back to its original orbit. During this action, it becomes something that is considered the human eye as colors. Furthermore, the atoms, amounting to trillions of these continue to do it every time, hence we see the "image" unbroken.

The mechanism of this stunning work is unmatched any man-made machines. A clock, for example, has a very complicated mechanism, and all parts (gears, discs, nuts, bolts, etc.) should be placed in the right location and in a proper way so that the clock works fine. If there are problems, though small, in the clock mechanism will be disturbed. But, when we think about the atomic structure and how the mechanism of electron-electron work, the simplicity of the structure of the clock can be better understood. As already mentioned, the mechanism of electrons is too complex, perfect, and flawless to be compared with any system of man-made. Clearly, a system with complexity is so amazing and so perfect is not running may appear spontaneously, as a result of accidental events such as the materialist scientists say. Now let us ask this question: When you walk in the desert and see a watch lying on the ground, whether you would think that the clock was formed from dust, sand, soil and rock by chance? No one would think that, because of the design and knowledge of the hour is too obvious. In fact, the design and knowledge in an atom as mentioned above is superior to anything man-made mechanism. The owner of this knowledge is God, who has supreme knowledge, who know, see, and made everything.

God created each "place" well we can see and that we can not see, with the goal of art is infinite and He gives grace to the countless we use, whether we realize it or not. Ins and outs of color that we have not known before, and we feel no need to learn it, has drawn our attention to detail and complexity as knowledge develops. It is inevitable that the development and advancement of science should cause everyone who uses reason and conscience to believe in the existence of God. Nevertheless, there are still people who ignore the breadth of arts and science goals that can be observed everywhere in the universe. A famous scientist, Louis Pasteur, provides interesting commentary on this by saying, "Science is a little distance you from God, but the knowledge that the closer you are to him" .23

When a person learn more about the examples of creation around him, he will better understand that God surrounded him from all directions, he set the whole affair in the heavens and the earth, and control everything. It understands that human life would be taken and received a reply to what he was doing in the world. When the believer is more familiar with the innumerable phenomena taking place around him, his admiration for Allah's knowledge increases. Admiration is a very important step towards recognition of the strength and unlimited power belong to Allah, and fear Him. This is stated in the Qur'an:

"Do you not see that Allah sends down rain from the sky and the rain that we produce the fruits of varying colors. And among the mountains there are streaks white and red variety of colors and some are black and so ( anyway) among humans, animals, reptiles and livestock animals are a variety of colors (and kind). Surely the fear of God among His servants, only the clergy. Allah is Mighty, Forgiving. " (Surah Fatir, 35: 27-28)

Photons from the sun that hit the object on the earth's structure allows us to see the world full of color.