1. Chemical Equations Theoretical Yield % Composition

2. How can the following equation best be interpreted? 4Al + 3O2 → 2Al2O3
8.1
1 mole Al reacts with 3 moles O2
1 mole Al produces 1 mole of Al2O3
1 mole Al produces 0.5 mole Al2O3
1 mole Al reacts with 2 moles of O2
1 mole Al cannot react with O2
Answer: c

3. How many moles of oxygen are needed to produce 6 moles of Fe2O3 in the following equation? Fe + 3O2 → 2Fe2O3
8.2 3 1 6 9 18
Answer: d

4. How many moles of gaseous oxygen are required for the complete combustion of 4.0 moles of butane (C4H10)?
8.3
4.0
8.0 13 26 52
Answer: d

5. How many grams of oxygen are required to completely burn 5
How many grams of oxygen are required to completely burn 5.90 g of C3H8 in the following unbalanced equation? C3H8(g) + O2(g) → CO2(g) + H2O(g)
8.4
5.90 g
21.4 g
4.28 g
10.7 g
29.5 g
Answer: b

6. How many grams of aluminum sulfate are produced from 2
How many grams of aluminum sulfate are produced from 2.67 mol sulfuric acid in the following unbalanced equation? Al2O3(s) + H2SO4(aq) → Al2(SO4)3(aq) + H2O(l)
8.5
305 g
457 g
272 g
914 g
342 g
Answer: a

7. How many moles of water are produced from the combustion of 3
How many moles of water are produced from the combustion of 3.5 mol of hydrogen and 5.2 mol of oxygen?
8.9
7.0 mol
5.2 mol
3.5 mol
10. mol
1.8 mol
Answer: c

8. How many molecules of water are produced from the combustion of 2
How many molecules of water are produced from the combustion of 2.56 mol of octane in the following equation? 2C8H O2 → 16CO2 + 18H2O?
8.12
1.08  1025 molecules
2.77  1025 molecules
2.56  1025 molecules
1.39  1025 molecules
6.02  1023 molecules
Answer: d

9. How many molecules of ammonia are produced from 7
How many molecules of ammonia are produced from 7.54  1025 molecules of hydrogen in the following equation: 3H2 + N2 → 2NH3?
8.14
2 molecules
7.54  molecules
5.03  molecules
1.51  molecules
6.02  molecules
Answer: c

10. What is the theoretical yield of acetic acid when 22
What is the theoretical yield of acetic acid when 22.5 g of methanol reacts with 32.0 g of carbon monoxide in the following equation? CH3OH + CO → HC2H3O2
8.16
24.2 g
32.0 g
42.2 g
68.6 g
84.4 g
Answer: c

11. What is the theoretical yield of SO3 from the combustion of 3
What is the theoretical yield of SO3 from the combustion of 3.00 mol of S and 6.00 mol of O2?
8.17
3.00 g
320. g
2.00 g
4.00 g
240. g
Answer: e

12. Which of the following statements is NOT correct about the limiting reactant in a reaction?
8.20
It has the lowest mass.
Its coefficient in the balanced equation is the smallest one.
It has the highest mass.
It doesn’t react completely.
All of the above
Answer: d

13. When methane, CH4, is burned in oxygen the theoretical yield is 28
When methane, CH4, is burned in oxygen the theoretical yield is 28.9 g CO2. A chemistry student performed the experiment and the yield was g CO2. What is the student’s percent yield?
8.21
100.%
91.3%
109%
85.2%
55.9%
Answer: b

14. 5. 0 kg of hydrogen is reacted with 31 kg of oxygen
5.0 kg of hydrogen is reacted with 31 kg of oxygen. The experiment yields 28 kg of water. Calculate the percent yield of the reaction.
8.24
40.%
63%
80.%
90.%
161%
Answer: c

15. Which of the following statements is/are true about the sign of ΔHrxn?
8.26
A negative enthalpy indicates that a reaction is endothermic.
A positive enthalpy indicates that a reaction is exothermic.
Energy flows out of the system in an exothermic reaction
Energy flows out of the system in an endothermic reaction.
Answer: c

16. Classify the following process appropriately: Water condensing
8.27
Endothermic, ΔH is positive
Exothermic, ΔH is negative
Exothermic, ΔH is positive
Endothermic, ΔH is negative
None of the above
Answer: b