For #CH_4 +2O_2 -> CO_2 + 2H_2O#, the molar mass of oxygen gas (#0_2#) is 32.00 g/mol. The molar mass of carbon dioxide (#CO_2#) is 44.01 g/mol. What mass of #CO_2#, in grams, will form when 8.94 g #O_2# completely react?
Consider the mass balance.
The balanced chemical equation tells us unequivocally that 16 g of methane gas reacts with 32 g of dioxygen gas to give 44 g of carbon dioxide, and 36 g of water. These masses represent the molar equivalence of reactants and products. You have to work the molar quantity of the given mass of dioxygen, and with how much methane it will react.