A balanced chemical equation is as when the number of atoms on
each side of the equation is the equal. for example if you have 12 hydrogens
on the left hand side of the equation, you must have 12 hydrogens on the right
hand side, if there are 4 oxygens on the left, there must be 4 oxygens on the
right, and so on. This is because of the law of conservation of mass - you
can't create or destroy atoms during a chemical reaction. But you can't just
add atoms.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.
a. If the selected element is already balanced, put the SAME letter coefficient at its blank lines.
b. If the element is not balanced, put
first the letter coefficient at the side with the GREATER number of
atoms for that element, and balance the other side in terms of the same
letter coefficient. For example, the letter coefficient could be “a” and
the coefficient for the other side could be “2a”.
c. Repeat step 1, if needed, with another letter coefficient.