Limiting Reactants

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

How much water can be made if 8 moles of NH₃ react with 6 moles of NO?

4NH₃+6NO --> 5N₂ + 6H₂O

• 5 moles

• 6 moles

• 12 moles

• 18 moles

In a balanced equation, the ratio between the coefficient of any two substances is called the _______.

• mole ratio

• stoichiometry

• limiting reactant

• excess reactant

In the image, which reactant is limiting?

• The white molecules, because there are extra.

• The black atoms, because they are completely used up.

• The white molecules, because they are completely used up.

• The black atoms, because there are extra.

Theoretical yield = 73g

Actual yield = 62g

Calculate the percent yield.

• 18%

• 118%

• 85%

• 15%

Use the equation 2 Al + 3 Cl₂ ---> 2 AlCl₃.  If 2 moles of aluminum and 2 moles of chlorine are reacted, identify the limiting reactant.

• AlCl3
• Cl2
• Al

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

What is the first thing you must do to solve a stoichiometry problem?

• Write a Balanced Equation
• Panic
• Write an Unbalanced Equation
• Avogadro's Number

For the Balanced Reaction: 3 Mg + 1 Fe₂O₃ → 3 MgO + 2 Fe; What is the Ratio of moles of MgO to moles Fe?

• 3mol Mg / 2 mol Fe
• 2 mol Mg/ 3 mol Fe
• 1 mol Fe/ 2 mol Fe
• 3 mol MgO / 2 mol Fe

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