Question

why is it important to balance an equation?

Answer 1

to keep the conservation of atoms , mass and energy its necessary to balance equation

Answer 2

I would say that what chmvijay says is why chemical equations can be balanced, but not why they should be balanced.

If you're a chemist and want a certain amount of a type of chemical, it allows you to predict how much of your reactants you should get so that you don't waste money buying too much or end up with less than you want.

Answer 3

because it is convenient for the chemists..it also helps us to understand the combination of reactants..for example
2(H2)+(O2)--->2(H2O)
which means if you want hydrogen and oxygen in a bottle to react completely, you need them to be in the ratio of 2:1 by volume ..which says that if you take one litre of hydrogen and one litre of oxygen they wont react completely...
so balancing gives us the idea to think in the atomic scale..