Calculate the mass (in grams) of water vapor produced when 56.0 grams of pure hydrogen gas burn in the air. Given the information from that, calculate the mass of oxygen gas that would be needed to burn 100 grams of hydrogen gas.

Answer 1

write the balanced chemical equation.

Notice the ratio of coefficents of H2 to O2

how many moles of H2 do you have in 100 grams. Do you need half that number of moles of O2? How many grams is that.