Percentage yields

Last updated: 02/04/2020

WJEC A-Level Chemistry Unit 1.3 – Chemical calculations Percentage yields

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Question 1 of 18

1. Question
What is the equation to work out percentage yield?
- Actual amount of product ÷ theoretical amount of product x 100
- Theoretical amount of reactant ÷ actual amount of reactant x 100
- Actual amount of reactant ÷ theoretical amount of reactant x 100
- Theoretical amount of product ÷ actual amount of product x 100
Question 2 of 18

2. Question
What is used to measure percentage yield?
- mol
- dm $^3$
- mol dm $^3$
- cm $^3$
Question 3 of 18

3. Question
What does percentage yield measure?
- The success of a laboratory preparation
- The percentage of a reactant
- The number of moles
- Amount made in a reaction
Question 4 of 18

4. Question
During a photosynthesis reaction, 5.25 dm $^3$ of carbon dioxide is used with an excess of water, 3.21 grams of glucose is obtained. What is the percentage yield of glucose? Leave your answer to two decimal places and use the following equation to help you.

CO $_2$ (g) + 6H $_2$ O(l) – > 6O $_2$ (g) + C $_6$ H $_{12}$ O $_6$ (aq)
- 8.15%
- 83.52%
- 24.52%
- 5.98%
Question 5 of 18

5. Question
During the electrolysis of water, 250 cm $^3$ of hydrogen is used with an excess of oxygen. 0.092 grams of water is obtained. What is the percentage yield of water? Leave your answer to one decimal place and use the following equation to help you.

2H $_2$ (g) + O $_2$ (g) – > 2H $_2$ O(l)
- 49.1%
- 12.6%
- 22.9%
- 4.2%
Question 6 of 18

6. Question
0.500 dm $^3$ of ethanol is oxidised with an excess of oxygen. 1.250 grams of acetic acid is obtained. What is the percentage yield of acetic acid? Leave your answer to three significant figures and use the following equation to help you.

CH $_3$ CH $_2$ OH(l) + O $_2$ (g) – > CH $_3$ COOH(aq) + H $_2$ O(l)
- 100%
- 94.3%
- 24.8%
- 10.4%
Question 7 of 18

7. Question
150 cm $^3$ of hydrochloric acid is reacted with an excess of zinc. 0.450 grams of zinc chloride is obtained. What is the percentage yield of zinc chloride? Leave your answer to two decimal places and use the following equation to help you.

Zn + 2HCl – > H $_2$ + ZnCl $_2$
- 52.79%
- 23.46%
- 77.45%
- 10.28%
Question 8 of 18

8. Question
164 cm $^3$ of copper is reacted with an excess of silver nitrate. 0.61 grams of copper nitrate is obtained. What is the percentage yield of copper nitrate? Leave your answer to one decimal place and use the following equation to help you.

Cu + 2AgNO $_3$ -> 2Ag + Cu(NO $_3$ ) $_2$
- 47.6%
- 23.5%
- 12.3%
- 84.2%
Question 9 of 18

9. Question
5.3 dm $^3$ of sodium hydroxide is reacted with an excess of hydrochloric acid. 2.205 grams of sodium chloride is obtained. What is the percentage yield of sodium chloride? Leave your answer to two significant figures and use the following equation to help you.

HCl + NaOH – > NaCl + H $_2$ O
- 17%
- 1.2%
- 23%
- 94%
Question 10 of 18

10. Question
500 cm $^3$ of barium chloride is reacted with an excess of silver nitrate. 0.915 grams of silver chloride is obtained. What is the percentage yield of silver chloride? Leave your answer to two decimal places and use the following equation to help you.

BaCl $_2$ + 2AgNO $_3$ – > 2AgCl + Ba(NO $_3$ ) $_2$
- 15.32%
- 14.25%
- 55.39%
- 74.51%
Question 11 of 18

11. Question
5.4 grams of calcium carbonate is reacted with an excess of hydrochloric acid. 3.015 grams of calcium chloride is obtained. What is the percentage yield of calcium chloride? Leave your answer to one decimal place and use the following equation to help you.

CaCO $_3$ + 2HCl – > CaCl $_2$ + H $_2$ CO $_3$
- 50.3%
- 21.5%
- 83.1%
- 19.7%
Question 12 of 18

12. Question
4.65 grams of sodium is reacted with an excess of water. 2.10 grams of sodium hydroxide is obtained. What is the percentage yield of sodium hydroxide? Leave your answer to two decimal places and use the following equation to help you.

2Na(s) + 2H $_2$ O(l) -> 2NaOH(aq) + H $_2$ (g)
- 25.97%
- 86.22%
- 44.24%
- 9.11%
Question 13 of 18

13. Question
10.5 dm $^3$ grams of hydrogen is reacted with an excess of silver nitrate. 67.3 grams of silver is obtained. What is the percentage yield of silver? Leave your answer to three significant figures and use the following equation to help you.

H $_2$ + 2AgNO $_3$ – > 2Ag + 2HNO $_3$
- 7.45%
- 33.1%
- 81.0%
- 71.3%
Question 14 of 18

14. Question
5.62 dm $^3$ of magnesium hydroxide is reacted with an excess of nitric acid. 2.4 dm $^3$ of magnesium nitrate is obtained. What is the percentage yield of magnesium nitrate? Leave your answer to one decimal place and use the following equation to help you.

Mg(OH) $_2$ + 2HNO $_3$ – > Mg(NO $_3$ ) $_2$ + 2H $_2$ O
- 42.7%
- 11.6%
- 99.6%
- 61.9%
Question 15 of 18

15. Question
50 grams of aluminium is reacted with an excess of oxygen. 10.5 dm $^3$ of aluminium oxide is obtained. What is the percentage yield of aluminium oxide? Leave your answer to one decimal place and use the following equation to help you.

4Al + 3O $_2[/latex - > 2Al[latex]_2$ O $_3$
- 47.3%
- 54.3%
- 87.1%
- 77.2%
Question 16 of 18

16. Question
34.50 grams of ethanoic acid is reacted with an excess of ethanol. 12,000 cm $^3$ of ethyl ethanoate is obtained. What is the percentage yield of ethyl ethanoate? Leave your answer to two decimal places and use the following equation to help you.

CH $_3$ COOH + C $_2$ H $_5$ OH - > CH $_3$ COOC $_2$ H $_5$ + H $_2$ O
- 8.70%
- 5.83%
- 18.46%
- 96.36%
Question 17 of 18

17. Question
0.0345 grams of hydrochloric acid is reacted with 0.05 grams of ethene. 0.0022 grams of ethyl chloride is obtained. What is the percentage yield of ethyl chloride? Leave your answer to one decimal place and use the following equation to help you.

HCl + C $_2$ H $_4$ - > C $_2$ H $_5$ Cl
- 3.6%
- 93.6%
- 10.2%
- 55.4%
Question 18 of 18

18. Question
0.56 grams of salicylic acid is reacted with 0.39 grams of ethanoyl chloride. 0.02 grams of aspirin is obtained. What is the percentage yield of aspirin? Leave your answer to one decimal place and use the following equation to help you.

C $_7$ H $_6$ O $_3$ (aq) + C $_2$ H $_3$ OCl(aq) -> C $_9$ H $_8$ O $_4$ (aq) + HCl(aq)
- 2.7%
- 54.7%
- 36.2%
- 77.3%