LIMITING REACTANT

LIMITING REACTANT• Limiting Reagent

• The reactant that is totally used up during the chemical reaction

• Limits the amount of product produced

EXCESS REACTANT• Excess Reagent

• The reactant present in a quantity that is greater than what is needed to react with the limiting reactant

• Remains after the limiting reactant has been used up

• What is the limiting reactant?

• What are the excess reactants?

STEPS1. Balance the equation

2. Identify the givens (there are 2!)

3. Identify what you want to find

4. Use stoichiometry to solve

5. The reactant with a smaller amount of product produced is the limiting reactant

6. The other reactant is in excess

How many grams of silver bromide (AgBr) can be formed when solutions containing 50.0 g of MgBr2 and 100.0 g of AgNO3 are mixed together? What is the limiting reactant?

What is in excess?

1 MgBr2 + 2 AgNO3 2 AgBr + 1 Mg(NO3)2

50.0 g MgBr2 1 mol MgBr2 2 mol AgBr 187.77 g AgBr

184.11 g MgBr2 1 mol MgBr2 1 mol AgBr

= 102 g AgBr

100.0 g AgNO3 1 mol AgNO3 2 mol AgBr 187.77 g AgBr

169.88 g AgNO3 2 mol AgNO3 1 mol AgBr

= 110.5 g AgBr

Limiting Reactant (LR) = MgBr2 Excess Reactant (ER) = AgNO3

How many grams of hydrogen chloride can be produced from 1.00 g of hydrogen and 55.0 g of

chlorine? What is the limiting reactant? What is in excess?

H2 + Cl2 HCl

1.00 g H2 1 mol H2 2 mol HCl 36.46 g HCl

2.02 g H2 1 mol H2 1 mol HCl= 36.1 g HCl

55.0 g Cl2 1 mol Cl2 2 mol HCl 36.46 g HCl

70.90 g Cl2 1 mol Cl2 1 mol HCl

= 56.6 g HCl

Limiting Reactant (LR) = H2 Excess Reactant (ER) = Cl2

How many grams of barium sulfate (BaSO4) will be formed from 200.0 g of barium nitrate (Ba(NO3)2) and 150.0 g of

sodium sulfate (Na2SO4)? What is the limiting reactant? What is in excess?

Ba(NO3)2 + Na2SO4 BaSO4 + NaNO3

200.0 g Ba(NO3)2 1 mol Ba(NO3)2 1 mol BaSO4 233.40 g BaSO4

261.35 g Ba(NO3)2 1 mol Ba(NO3)2 1 mol BaSO4

= 178.6 g BaSO4

150.0 g Na2SO4 1 mol Na2SO4 2 mol BaSO4 233.40 g BaSO4

142.05 g Na2SO4 2 mol AgNO3 1 mol BaSO4

= 246.5 g BaSO4

Limiting Reactant (LR) = Ba(NO3)2 Excess Reactant (ER) = Na2SO4