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how to balance a chemical equation

Balancing a chemical equation:

• Find out how many atoms of each type are on each side of the equation.
• Next, look for an element which is in only one chemical on the left and in only one on the right of the equation.
• To balance that element, multiply the chemical species on the side which doesn't have enough atoms of that type by the number required to bring it up to the same as the other side.
• The number is called the coefficient.
• Now look for the next element or species that is not balanced and do the same thing.

Eg:

Unbalanced Equation:- C₃H₈ + O₂ ---> H₂O + CO₂

There are three carbons on the left, but only one on the right.
There are eight hydrogens on the left but only two on the right.
There are two oxygens on the left but three on the right.

Balanced Equation:- C₃H₈ + 5O₂ ---> 4H₂O + 3CO₂

In Example above, balance the carbons first, by putting a 3 in front of the CO₂, then balance the hydrogens by putting a 4 in front of H₂O and finally the oxygens (which are in more than one compound on the right, so we leave them until last) by putting a 5 in front of the O₂.