In order to balance a chemical equation, the amount of each compound or element must be the same on both sides. Refer to the law: Mass can neither be created nor destroyed. Here is an example:
Na + O2 --> NaO
There are two oxygen molecules because it is a diatomic. The aforementioned chemical equation is NOT balanced. Below is the balanced chemical equation:
2Na + O2 --> 2NaO
Chemical reactions take place between molecules of different elements and/or compounds and producing other elements and/or compounds. A chemical equation represents this process symbolically by an equation using chemical symbols of all the elements and compounds involved in the reaction. The symbols of the original elements involved in the reaction are represented on the left hand side of the equation and and those resulting from the reaction are represented on the right hand side. For example, consider the chemical equation given below.
NaOH + HCl --> NaCl + H2O
It represents that 1 molecule of NaOH combines with 1 molecule of HCl to produce 1 molecule of NaCl plus 1 molecule of water. Note that this reaction involves four different elements Na, Cl, H and O. If we count the number of atoms of each of these atoms we find that number of atoms of each element on left hand side is same as number of atoms on right hand side. A chemical equation of this type is called a balanced equation. And balancing of a chemical equation means changing the number of molecules of different elements and compounds on either side of a chemical equation so that number of atoms of each each element will be same on left and right hand side of the equation. To see how we can do this, let us consider the reaction involving hydrogen (H2) combining with oxygen (O2) to produce water (H2O). To represent it in the form of a chemical equation we write:
H2 + O2 --> H2O
In the above equation we find that atoms of hydrogen are 2 on each side of the equation, bud there are 2 atoms of oxygen on the left hand side but only one on the right hand. Therefore the equation is not balanced. On examination we find that the number of atoms of hydrogen involved in the reaction is twice the number of atoms of oxygen. Therefore we will need to double the number of hydrogen atoms. To do this we rewrite the equation as:
2H2 + O2 --> 2H2O
The equation is now balanced.
There are no hard and fast rules for balancing the chemical equation. To a large extent it is a matter of trial and error. It is best to start with an equation that contains just one molecule of all the substances involved in the reaction, and then counting the number of atoms of each element on both sides. If these are balance, nothing more need to be done. If not, increase the number of molecules on respective sides containing atoms of elements that fall short of required numbers. Some times this can involve several iterations. before a perfectly balanced equation is obtained.
how can i balance chemical eqation?