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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
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