Limiting Reagents

Limiting Reagent - reagent completely consumed in a reaction reagent - a substance or mixture for use in chemical analysis or other reactions

• determines the maximum amount of product formed

Steps:

1. Identify the limiting reagent (by determining the # of moles of each reaction)
2. Calculate the amount of product from the limiting reagent

Examples:

What mass of hydrogen is produced when 19.62g of zinc is reacted with 18.96g of hydrochloric acid

Zn(s) + 2 HCl(aq) -> ZnCl(aq) + H(g)

19.62g 18.96g

n = m / M = 19.62g / 65.39 g / mol = 0.300688178 mol

n = m / M = 18.96g / 36.46 g / mol = 0.520021941 mol

# moles HCl needed = 0.300688178 mol Zn * 2 mol HCl / 1 mol Zn = 0.60376357 mol

Limiting reagents have to be 1 of the reactants

Homework (Grade 11 Chemistry) p.309 # 31 - 39, 7 - 12 p.311 # 40 - 50 p.313 # 1 - 11