Analía Bellizzi – Chemistry Classes

Ronald Reagan Senior High School

# Limiting Reactants Exercises

## LIMITING REACTANT EXERCISES

1) Aluminum reacts with oxygen gas to produce aluminum oxide.

#### 4 Al   +   3 O2 2 Al2O3

Sketch 2 containers representing beakers, one on the left and another on the right of an arrow.
Draw 10 atoms of aluminum and 6 molecules of oxygen gas in the container on the left.
In the right container, sketch the contents after the reaction is complete.
(Ar: Al=27; O=16)

1. What is the limiting reactant?
2.  How many atoms or molecules of the excess reactant remain? 2) If a reaction vessel contains 0.15 mol K2O2 and 0.10 mol H2O.

(Ar: K=39; O=16; H=1)

#### 2 K2O2 + 2 H2O 4 KOH + O2

a. Which is the limiting reactant? Ans: H2O

b. Which is the reactant in excess? Ans: K2O2

c. How many grams of KOH will form? Ans:11.2

d. How many Liters of Oxygen gas will be released?  Ans: 1.2

3)Take the reaction:

#### 4 NH3 +5 O2 4 NO + 6 H2O.

In an experiment, 3.25 g of NH3 are allowed to react with 3.50 g of O2.

a. Which reactant is the limiting reagent?  Ans:  O2
b. How many grams of NO are formed?   Ans:  2.63 g NO
c. How much of the excess reactant remains after the reaction?    Ans: 1.76 g NH3 left

4) If 4.95 g of ethylene (C2H4) are combusted with 3.25 g of oxygen.

#### C2H4 + 3 O2 2 CO2  +  2 H2O

a. What is the limiting reagent?    Ans: O2
b. How many grams of CO2 are formed?    Ans: 2.99 g CO2
c. How many grams of excess remain in the vessel Ans:4.00g
d. How many mL of water vapor will be released into the air?  Ans: 1632 mL

5) If 21.4 g of aluminum is reacted with 91.3 g of iron(III) oxide, the products will be aluminum oxide and iron metal.
(Ar: Al=27; O=16; Fe=56)

#### Fe2O3  + 2 Al Al2O3 + 2 Fe

1.  What mass of iron will be produced? Ans: 44.39g
2. How much non limiting reactant is left? Ans:27.89 g

6) If 15 grams of copper react with 20 g of silver nitrate. How much silver can be formed? (be careful. You need to calculate the limiting reactant to be able to answer the question)
(Ar: Cu=64; O=16; Ag=108)

1.