Question

500.0 g of ammonia react with 51.0 moles of sulfuric acid to produce ammonium sulfate. How many moles of excess sulfuric acid are left over after the reaction is complete?

2 NH3 (aq) + H2SO4(aq) → (NH4)2SO4 (aq)

Answer 1

This is a limiting reagent problem. I know that because BOTH reactants are given. I solve these by solving two simple stoichiometry problems (simple meaning they are NOT limiting reagent problems); one for one reactant and another for the other reactant. Here is an solved example of a simple stoichiometry problem. Just follow the steps. Remember moles = grams/molar mass or moles = M x L.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Post your work if you get stuck and I can help you through it.