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.