In the reaction represented by the equation CH4(g) + 2O2(g) → CO2(g) + 2H2O(g), a - CO2(g) + 2H2O(g), a mass of 125 g CH. is reacted with excess oxygen. The expression 1 mol CH4 2 mol H20 18.02 g H20 125 g CH4 X 16.05 g CH4 1 mol CH4 1 mol H20 is used to calculate the: х a. b. mass of carbon dioxide produced. mass of oxygen reacted.