Question

How many liters of chlorine gas can react with 56.0 grams of calcium metal at standard temperature and pressure? Show all of the work used to find your answer.

Ca + Cl2 CaCl2

Answer 1

56 g of Ca -->1.40 mol Ca (divide grams by molar mass to get # of moles).
Each mol of Ca reacts with one mol of Cl2, so you need 1.40 mol. @ stp, 1 mol = 22.4 L. So multiply 1.40 mol x 22.4 L/mol = 31.30 L of Cl2.