Limiting & Excess Reactant and % Yield

What is a limiting reactant?

• the reactant that determines how much product can be made
• the reactant that is in excess
• the product that you can make the most of
• the amount of reactants that react with each other

Tags

NGSS.HS-PS1-7

You need 2 pieces of bread, 1 tablespoon of peanut butter and 2 tablespoons of jelly to make a sandwich.  If you have 10 pieces of bread, 4 tablespoons of peanut butter and 20 tablespoons of jelly, what is the limiting reactant?

• bread
• jelly
• peanut butter
• sandwich

What is the limiting reactant if 16 moles of NH₃ and 30.0 moles of NO are combined?

4NH₃ + 6NO --> 5N₂ + 6H₂O

• NH₃

• NO

• N₂

• water

Tags

NGSS.HS-PS1-7

CH₄ + 2H₂O --> CO₂ + 4H₂

What is the limiting reactant when 20g CH₄ and 15g H₂O are combined?

(Molar masses: CH₄ = 16.05 g/mol; H₂O = 18.02 g/mol, CO₂ = 44.01 g/mol, H₂ = 2.02 g/mol)

• CH₄

• H₂O

• CO₂

• H₂

Tags

NGSS.HS-PS1-7

2 Fe + 3 S --> Fe₂S₃

If 7.62g Fe and 8.67g S are combined, what is the limiting reactant?

(Molar masses: Fe = 55.85 g/mol; S = 32.07 g/mol, Fe₂S₃ = 207.91 g/mol)

• Fe

• S

• FeS

• none

Tags

NGSS.HS-PS1-7

When does a chemical reaction stop?

• When the lab is finished
• When the excess reactant is used up
• When the limiting reactant is used up
• Chemical reactions never stop

SO₂ + PCl₅ --> SOCl₂ + POCl₃

How much SOCl₂ is produced when 16.2g SO₂ are combined with 13.7g PCl_5?

(Molar masses: SO₂ = 64.07 g/mol; PCl₅ = 208.22 g/mol, SOCl₂ = 118.97 g/mol)

• 7.83g

• 30.1g

• 26.4g

• 19.8g

Tags

NGSS.HS-PS1-7

3CaCO₃ + 2FePO₄ --> Ca₃(PO₄)₂ + Fe₂(CO₃)₃

If 100. g of CaCO₃ is reacted with 45 g of FePO₄, what is the limiting reactant? (molar masses: CaCO₃ = 100.09 g/mol; FePO₄ = 150.82 g/mol; Ca₃(PO₄)₂ = 310.18 g/mol; Fe₂(CO₃)₃ = 291.73 g/mol)

• iron(III) carbonate, Fe₂(CO₃)₃

• calcium carbonate, CaCO₃

• iron(III) phosphate, FePO₄

• calcium phosphate, Ca₃(PO₄)₂

Tags

NGSS.HS-PS1-7

NGSS.HS-PS1-2

3CaCO₃ + 2FePO₄ --> Ca₃(PO₄)₂ + Fe₂(CO₃)₃

What is the maximum amount of each product that can be formed if 100. g CaCO₃ and 45.0 g FePO₄ are reacted?

(molar masses: CaCO₃ = 100.09 g/mol; FePO₄ = 150.82 g/mol; Ca₃(PO₄)₂ = 310.18 g/mol; Fe₂(CO₃)₃ = 291.73 g/mol)

• 103 g of calcium carbonate, 97.1 g of iron(III) phosphate

• 92.5 g of calcium phosphate, 87.0 g of iron(III) carbonate

• 310. g of calcium phosphate, 291 g of iron(III) carbonate

• 46.3 g of calcium phosphate, 43.5 g of iron(III) carbonate

Tags

NGSS.HS-PS1-7

NGSS.HS-PS1-2

A reactant that remains after a chemical reaction stops

• stoichiometric reactant

• molar mass

• excess reactant
• limiting reactant