How would you balance this chemical equation: #C_3H_8 + O_2 -> 3CO_2 + 4H_2O#?
Let's look for each element one by one to see which element(s) needs balancing.
Carbon is balanced : there are 3 carbon atoms on the LHS, and 3 carbons on the RHS.
Hydrogen is balanced : There are 8 hydrogen atoms on the LHS, and 4 of 2 hydrogen atoms on the RHS, making it 8 atoms in total.
Oxygen is not balanced : there are 2 oxygen atoms on the LHS, but 10 oxygens on the RHS.
How many times does 2 go into 10? The answer is 5
There are 6 carbon atoms, 16 hydrogen atoms and 14 oxygen atoms on each side of the equation. It is now balanced.