Question: how to calculate how many moles are needed to react?
Answer: Find Mass in Grams. Calculate the mass in grams of each reactant. ... 
Find Atomic Weight. Determine the atomic weight of each element using the periodic table. ... 
Calculate Grams per Mole. ... 
Divide Grams by Grams per Mole. ... 
Find Reaction Coefficients. ... 
Determine Limiting Reactant. ... 
Determine Product Mass. ... 
Compare Reaction Results.