Limiting Reagents

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

The limiting reactant . . .

• slows the reaction down.

• is used up first.

• is the reactant that is left over.

• controls the speed of the reaction.

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.

3. The reactant that is not completely used up in a chemical reaction is called the __________ .

• spectator reagent
• limiting reagent
• excess reagent
• catalyst

Why is it important to identify the limiting reagent?

• The limiting reagent speeds up the reaction.

• The limiting reagent controls the amount of product formed.

• If there is no limiting reagent, the reaction will not occur.

• No stoichiometry calculations can be done without a limiting reagent.

When 12 moles of O₂ reacts with 6 moles of C₁₀H₈, what is the limiting reactant?  
1 C₁₀H₈ + 12 O₂ --> 10 CO₂ + 4 H₂O

• Oxygen
• C₁₀H₈
• Water
• Carbon Dioxide

1 P₄ + 3 O₂ --> 1 P₄O₆ 
What is the limiting reactant if 12 moles of P₄ react with 15 moles of O₂?

• P₄
• O₂
• P₄O₆ 
• none of the above

6.02 x 10²³

• Mole Day

• Avogadro's Number

• Avodagro's Number

• Mol Day

Refers to the reactant that limits the yield of the product. It is also the reactant that runs out first and produced the LEAST amount of product.

• Limiting Reagents or Limiting Reactant

• Excess Reagent or Excess Reactant

The reactant that is left over and produced the GREATEST amount of product.

• Limiting Reagents or Limiting Reactant

• Excess Reagent or Excess Reactant