which chemical equation is balanced?
Balance the oxygen atoms. 1  Because you've added coefficients to the molecules on the right side of the equation, the number of oxygen atoms has changed. 2  Add a coefficient of 5 to the oxygen molecule on the left side of the equation. 3  C3H8 + 5O2 --> 4H2O + 3CO2.  The carbon, hydrogen, and oxygen atoms are balanced.