Balancing Chemical Equations

Balancing chemical equations is one of the important topic in chemistry. An equation is balanced when the same number of each element is represented on the reactant and product sides. Equations must be balanced to accurately reflect the law of conservation of matter.

With that said, lets see how to balance chemical equations. Lets take this equation:

N2 + H2 ------------> NH3

First make a column and write the elements with the number. Like this:

Reactants:                                       Products: 

N - 2                                                N - 1

H - 2                                                 H - 3

From  this we can tell that Nitrogen (N) is not same. So to make it same we can multiply the product Nitrogen with 2 to make it equal. Since Hydrogen (H) is a compound with Nitrogen, Hydrogen will also be multiplied with 2. 

Reactants:                                       Products: 

N - 2                                          N - 1 x 2 = 2

H - 2                                          H - 3 x 2 = 6

Now, Nitrogen is balanced, and Hydrogen is not. We can multiply Hydrogen in the reactant side by 3 to make it balanced. Since Hydrogen is all by itself, we won't multiply Nitrogen in the reactants side by 3.

Reactants:                                           Products: 

N - 2                                                      N - 2

H - 2 x 3                                                 H - 6

Now we have balanced it. But we won't write it like this. We have to add the numbers we multiplied in the equation.

N2 + 3H2 ----------------> 2NH3

And we have balanced this equation.

Here is a picture which has another example:

- Mirage Chemistry