Question

Hydrogen gas reacts with oxygen gas to produce water vapor. You react 2.00 grams of a hydrogen with 2.00 grams of oxygen and you make 0.100 grams of water.

a) What is the balanced equation for the reaction?

b) How many grams should the resulting gas mixture weigh?

c) What should have been the theoretical yield for the reaction?

d) What is the percent yield of the reaction?

Answer 1

a)
2H2 (g) + O2 (g) ------> 2H2O (g)

b)
using conservation of mass,
gas mixture will always weight 2.00 + 2.00 = 4.00 g

c)
since molar mass is more for O2 but mass is same for both H2 and O2, O2 is limiting reagent here.
moles of O2 reacting = mass of O2/molar mass of O2
= 2/32 mol

moles of H2O formed = 2* moles of O2 reacting
= 2*2/32 mol
= 1/8 mol

mass of H2O formed = number of moles * molar mass
= 18*1/8
=2.25 g
Answer: 2.25 g

d)
actual mass = 0.100 g
percent yield = 0.100*100/2.25 = 4.44 %
Answer: 4.44 %