Percentage yield
11th grade (Year 12 in England) · 16 questions · Common Core: NGSS.HS-PS1-7 · England: GCSE Chemistry: Quantitative chemistry (yield)
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Question 1
Why do chemical companies want high percentage yields?
- A. Less raw material is wasted, so it is cheaper and more sustainable
- B. It increases the activation energy
- C. It is required for all reactions to happen
- D. It makes the product more colourful
Question 2
CaCO₃ → CaO + CO₂ (Mr: CaCO₃ = 100, CaO = 56). 50 g of calcium carbonate was heated and 22.4 g of calcium oxide was collected. What is the percentage yield? Give 1 decimal place.
Answer%
Question 3
A reaction could make 25 g of product in theory, but 21.25 g was actually collected. What is the percentage yield?
Answer%
Question 4
A student calculates a yield of 112 %. What is the most likely explanation?
- A. The product was still wet or impure when weighed
- B. The theoretical yield is always too high
- C. The yield is excellent
- D. The reaction created extra atoms
Question 5
CaCO₃ → CaO + CO₂ (Mr: CaCO₃ = 100, CaO = 56). 25 g of calcium carbonate was heated and 12.6 g of calcium oxide was collected. What is the percentage yield? Give 1 decimal place.
Answer%
Question 6
A reaction could make 120 g of product in theory, but 72 g was actually collected. What is the percentage yield?
Answer%
Question 7
Why do chemical companies want high percentage yields?
- A. It makes the product more colourful
- B. Less raw material is wasted, so it is cheaper and more sustainable
- C. It increases the activation energy
- D. It is required for all reactions to happen
Question 8
CaCO₃ → CaO + CO₂ (Mr: CaCO₃ = 100, CaO = 56). 50 g of calcium carbonate was heated and 22.4 g of calcium oxide was collected. What is the percentage yield? Give 1 decimal place.
Answer%
Question 9
A reaction could make 20 g of product in theory, but 19 g was actually collected. What is the percentage yield?
Answer%
Question 10
A student's yield is low because some crystals were left stuck to the filter paper. How could they improve it?
- A. rinse the filter paper with a little cold solvent to recover more product
- B. use less of each reactant
- C. weigh the product while it is still wet
- D. throw away the first crystals
Question 11
CaCO₃ → CaO + CO₂ (Mr: CaCO₃ = 100, CaO = 56). 100 g of calcium carbonate was heated and 47.6 g of calcium oxide was collected. What is the percentage yield? Give 1 decimal place.
Answer%
Question 12
A reaction could make 25 g of product in theory, but 22.5 g was actually collected. What is the percentage yield?
Answer%
Question 13
Why do chemical companies want high percentage yields?
- A. It is required for all reactions to happen
- B. It makes the product more colourful
- C. Less raw material is wasted, so it is cheaper and more sustainable
- D. It increases the activation energy
Question 14
CaCO₃ → CaO + CO₂ (Mr: CaCO₃ = 100, CaO = 56). 20 g of calcium carbonate was heated and 10.08 g of calcium oxide was collected. What is the percentage yield? Give 1 decimal place.
Answer%
Question 15
A reaction could make 40 g of product in theory, but 38 g was actually collected. What is the percentage yield?
Answer%
Question 16
A student calculates a yield of 112 %. What is the most likely explanation?
- A. The product was still wet or impure when weighed
- B. The theoretical yield is always too high
- C. The reaction created extra atoms
- D. The yield is excellent
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