Question

What is the percent yield of the mass of water that will be produced when 5.0 grams of H2 is reacted with
excess O2 if 40. g of water are actually recovered?

Answer 1

Find the theoretical yield from this example.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Then %yield = (40.0g/theoretical yield)*100 = ??