Consider the equation for the formation of water.

2H2 + O2 - --> 2H2O

What is the theoretical yield of H2O if 130 g of H2O is produced from 18 g of H2 and an excess of O2?

The theoretical yield is 160 g H₂O.

Moles of H₂ = 18 g H₂ * (1 mol H₂/2.016 g H₂) = 8.93 mol H₂

Moles of H₂O = 8.93 mol H₂O * (2 mol H₂O/2 mol H₂) = 8.93 mol H₂O

Theoretical yield of H₂O = 8.93 mol H₂O * (18.02 g H₂O/1 mol H₂) = 160 g H₂O