homeworkchapter09.htmlTEXTsfri"ܽĽ۸l F.J. DeHoratius HW 9.6 4

Chapter 9



Homework 9.1 Molar Ratio Problems

1. For each of the following chemical equations write all possible mole ratios.

e.g. for the equation 2 Al2O3 ---> 4 Al + 3 O2

the answer is 2 mol of Al2O3 for each 4 mol of Al
4 mol of Al for each 2 mol of Al2O3
2 mol of Al2O3 for each 3 mol of O2
3 mol of O2 for each 2 mol of Al2O3
4 mol of Al for each 3 mol of O2
3 mol of O2 for each 4 mol of Al

a) 2 HgO ---> 2 Hg + O2

b) 4 NH3 + 6 NO ---> 5 N2 + 6 H2O

c) 2 Al + 3 H2SO4 ---> Al2(SO4)3 + 2 H2

2. For each of the following chemical equations write all possible mole ratios:

a) 2 Ca + O2 ---> 2 CaO

b) Mg + 2 HF ---> MgF2 + H2

Homework 9.2 Molar Mass Problems

1. For the following equations determine to two decimal places the molar masses of all substances involved:

a) 2 HgO ---> 2 Hg + O2

b) 4 NH 3 + 6 NO ---> 5 N2 + 6 H2O

c) 2 Al + 3 H2SO4 ---> Al2(SO4)3 + 2 H2

d) 2 Ca + O 2 ---> 2 CaO

e) Na2CO3 + Ca(OH)2 ---> 2 NaOH + CaCO3
f) Mg + 2 HF ---> MgF2 + H2

Homework 9.3 Mole-Mole Problems

1. How many moles of ammonia are produced when 6 mol of hydrogen gas react with an excess of nitrogen gas according to the following balanced equation:

3 H2 + N2 ---> 2NH3

(ans: 4 mol) (solution)


2. How many moles of potassium chlorate are needed to produce 15 mol of oxygen according to the following balanced equation:

2 KClO3 ---> 2 KCl + 3 O2

(ans: 10. mol) (solution)


3. Given the following balanced equation:

4 NH3 + 3 O2 ---> 2 N2 + 6 H2O


a) How many moles of oxygen will be need to react with 4 mol of NH3? (ans: 3 mol) (solution)
b) How many moles of N2 will be produced when 4 mole of NH3 react with oxygen? (ans: 2 mol) (solution)
c) How many moles of water will be produced when 4 mole of NH3 react with oxygen? (ans: 6 mol) (solution)
d) How many moles of NH3 will be needed to produce 4 mol of N2? (ans: 8 mol) (solution)
e) How many moles of oxygen will be needed to produce 4 mol of N2? (ans: 6 mol) (solution)
f) How many moles of water will be produced when 4 mol of N2 are produced? (ans: 12 mol) (solution)

4. How many moles of oxygen are required to react with 4.50 mol of ethane, C2H6 according to the following balanced equation:

2 C2H6 + 7 O2 ---> 4 CO2 + 6 H2O

(ans: 15 mol) (solution)

Homework 9.4 Mole-Mass / Mass-Mole Problems

1. When magnesium burns in air, it combines with oxygen to form magnesium oxide according to the following balanced equation:

2 Mg + O2 ---> 2 MgO

What mass of magnesium oxide is produced from 2.00 mol of magnesium? (ans: 80.6 g) (solution)

2. What mass in grams of oxygen combines with 2.00 mol of magnesium according to the above reaction?

(ans: 32.0 g) (solution)

3. What mass of glucose can be produced from a photosynthesis reaction that occurs using 10 mol of CO2 according to the following balanced equation:

6 CO2 + 6 H2O ----> C6H12O6 + 6 O2

(ans: 30.3 g) (solution)

4. Sodium chloride is produced from its elements according to the following balanced equation:

2 Na + Cl2 ---> 2 NaCl
a)What mass of sodium would be required to produce 25.0 mol of sodium chloride? (ans: 574.8 g) (solution)
b) What mass of chlorine would be required to produce 25.0 mol of sodium chloride? (ans: 886.3 g) (solution)

5. How many moles of mercury (II) oxide, HgO, are needed to produce 125 g of oxygen according to the following balanced equation:

2 HgO ---> 2 Hg + O2

(ans: 7.81 mol) (solution)

6. How many moles of mercury are produced when 125 g of oxygen are produced according to the equation above? (ans: 7.81 mol) (solution)

7. What mass of HCl is consumed by the reaction of 2.50 mol of magnesium according to the following balanced equation:

Mg + 2 HCl ---> MgCl2 + H2

(ans: 182 g) (solution)

8. How many moles of water are needed to react with 32.0 g of calcium carbide to produce acetylene, C2H2, according to the following balanced equation:

CaC2 + 2 H2O ---> C2H2 + Ca(OH)2

(ans: 0.998 mol) (solution)


Homework 9.5 Mass-Mass Problems

1. How many grams of ammonium nitrate are required to produce 33.0 g of N2O, nitrous oxide or laughing gas, according to the following balanced equation:

NH4NO3 ---> N2O + 2 H2O

(ans: 60.0 g) (solution)


2. How many grams of water are produced when 33.0 g of nitrous oxide are produced according to the above reaction? (ans: 27.0 g) (solution)

3. What mass of silver is produced from 100 g of copper according to the following balanced equation:

Cu + 2 AgNO3 ---> Cu(NO3)2 + 2 Ag

(ans: 340. g) (solution)

4. What mass of aluminum is produced by the decomposition of 50 g of aluminum oxide according to the following balanced equation:

2 Al2O3 ---> 4 Al + 3 O2

(ans: 26.46 g) (solution)


5. What mass of AgCl is produced from 75.0 g of AgNO3 according to the following balanced equation:

NaCl + AgNO3 ---> NaNO3 + AgCl

(ans: 63.3 g) (solution)

6. How many grams of carbon dioxide are produced when 250 g of acetylene, C2H2, react with oxygen according to the following balanced equation:

2 C2H2 + 5 O2 ---> 4 CO2 + 2H2O

(ans: 845 g) (solution)

Homework 9.6 Limiting Reactant Problems

1. Which is the limiting reactant when 0.750 mol of N2H4, hydrazine, reacts with 0.50 mol of hydrogen peroxide according to the following balanced equation:

N2H4 + H2O2 ---> N2 + 4 H2O
(solution) (alternate solution)

2. If 20.5 g of chlorine is reacted with 20.5 g of sodium which reactant is in excess and which is the limiting reactant according to the following balanced equation:

2 Na + Cl2 ---> 2 NaCl

(solution)

3. If 2.00 mol of Zn are heated with 1.00 mol of sulfur, identify the limiting reactant for the following balanced equation:

8 Zn + S8 ---> 8 ZnS

(solution)

4. a) If 2.40 mol of carbon are exposed to 3.10 mol of steam, identify the limiting reactant in the following balanced equation:

C + H2O ---> H2 + CO

(solution)

b) How many moles of excess reactant remain? (solution)

Homework 9.7 Percent Yield Problems

1.
If 75.0 g of CO reacts to produce 68.4 g CH3OH, methanol, what is the percent yield of methanol according to the following balanced equation:

CO + 2 H2 ---> CH3OH

(solution)

2. When 200 g of calcium carbonate are heated the actual yield of calcium oxide is 105 g. What is the percent yield if the the following is the balanced equation:

CaCO3 ---> CaO + CO2

(solution)