Name: _______________________ Chemistry Period: _______ March 30, 2016

STOICHIOMETRY PRACTICE HANDOUT – Answer Key

1. Balance the following chemical reaction: 2 C4H10 + 13 O2 è 8 CO2 + 10 H2O, and show what the following molar ratios should be.

a. 2 mol C4H10 / 13 mol O2 b. 13 mol O2 / 8 mol CO2 c. 13 mol O2 / 10 mol H2O d. 2 mol C4H10 / 8 mol CO2 e. 2 mol C4H10 / 10 mol H2O

2. Balance the following equation: 2 KClO3 è 2 KCl + 3 O2

a. How many moles of O2 can be produced by letting 14.00 moles of KClO3 react?

14 mol KClO3 × 3 mol O2

2 mol KClO3 = 21 mol O2

b. How many moles of KCl can be produced by letting 14.00 moles of KClO3

react?

14 mol KClO3 × 2 mol KCl

2 mol KClO3 = 14 mol KCl

3. Balance the following equation: 2 K + __ Cl2 è 2 KCl

a. How many grams of KCl is produced from 3.50 g of K?

3.50 g K × 1 mol K39 g K

× 2 mol KCl2 mol K

× 74 g KCl

1 mol KCl=6.6 g KCl

b. How many grams of KCl is produced from 2.00 g of Cl2?

2.00 g Cl2 × 1 mol Cl270 g Cl2

× 2 mol KCl1 mol Cl2

× 74 g KCl

1 mol KCl= 4.23 g O2

4. Balance the following equation: __ Na2O + __ H2O è 2 NaOH

a. How many grams of NaOH is produced from 1.30 x 102 grams of Na2O?

130 g Na2O × 1 mol Na2O 62 g Na2O

× 2 mol NaOH1 mol Na2O

× 40 g NaOH

1 mol NaOH=168 g NaOH

Name: _______________________ Chemistry Period: _______ March 30, 2016

b. How many grams of Na2O are required to produce 1.75 x 102 grams of NaOH?

175 g NaOH × 1 mol NaOH40 g NaOH

× 1 mol Na2O2 mol NaOH

× 62 g Na2O1 mol Na2O

=136 g Na2O

5. Balance the following equation: 8 Fe + __ S8 è 8 FeS

a. What mass of iron is needed to react with 12.0 grams of sulfur?

12.0 g S8 × 1 mol S8256 g S8

× 8 mol Fe1 mol S8

× 56 g Fe

1 mol Fe=21 g Fe

b. How many grams of FeS are produced from 12.0 grams of sulfur?

12.0 g S8 × 1 mol S8256 g S8

× 8 mol FeS1 mol S8

× 88 g FeS1 mol Fe

= 33 g FeS

6. Balance the following equation: 2 NaClO3 è 2 NaCl + 3 O2

a. 13.00 moles of NaClO3 will produce how many grams of O2?

13 mol NaClO3 × 3 mol O2

2 mol NaClO3 ×

32 g O2

1 mol O2=624 g O2

b. How many grams of NaCl are produced when 75.0 grams of O2 are

produced?

75.0 g O2 × 1 mol O2

32 g O2 ×

2 mol NaCl3 mol O2

× 58 g NaCl

1 mol NaCl = 91 g NaCl

7. Balance the following equation: __ Cu + 2 AgNO3 è __ Cu(NO3)2 + 2 Ag

a. How many moles of Cu are needed to react with 3.50 moles of AgNO3?

3.50 mol AgNO3 × 1 mol Cu

2 mol AgNO3=1.75 mol Cu

b. If 88.5 grams of Ag were produced, how many grams of Cu reacted?

88.5 g Ag × 1 mol Ag108 g Ag

× 1 mol Cu2 mol Ag

× 63.5 g Cu1 mol Cu

= 26 g Cu

Name: _______________________ Chemistry Period: _______ March 30, 2016 8. Molten iron and carbon monoxide are produced in a blast furnace by the reaction of iron(III) oxide and pure carbon.

a. Write the balanced equation:

Fe2O3 + 3C → 2Fe + 3CO

b. If 20.0 kilograms of pure iron (III) oxide is used, how many kilograms of iron can be produced?

20.0 kg Fe2O3 × 1000 g Fe2O3

1 kg Fe2O3 ×

1 mol Fe2O3

160 g Fe2O3 ×

2 mol Fe1 mol Fe2O3

× 55.8 g Fe1 mol Fe

× 1 kg Fe

1000 g Fe=14 kg Fe

9. The average human requires 115.0 grams of glucose (C6H12O6) per day. The photosynthetic reaction is: 6 CO2 + 6 H2O è __ C6H12O6 + 6 O2

a. How many grams of CO2 (in the photosynthesis reaction) are required for

this amount of glucose?

115.0 g Glucose × 1 mol Glucose180 g Glucose

× 6 mol CO2

1 mol Glucose ×

48 g CO2

1 mol CO2 =184 g CO2

10. Balance the following reaction:

4 NH3 (g) + 5 O2 (g) è 4 NO (g) + 6 H2O (l)

a. What is the total number of moles of products formed when 1.50 moles of ammonia (NH3) reacts?

1.50 mol NH3 × 4 mol NO4 mol NH3

=1.5 mol NO

1.50 mol NH3 × 6 mol H2O4 mol NH3

=2.25 mol H2O

Total #moles produced = 1.5 mol NO + 2.25 mol H2O = 3.75 mol