RPAL Percent Yield 2 — Questions and Answers
Question 1: A reaction has a theoretical yield of 25 g and a percent yield of 72%. What is the actual yield?
- 18 g (Correct answer)
- 34.7 g
- 72 g
- 25 g
Correct answer: 18 g
Actual yield = (72/100) × 25 g = 18 g.
Question 2: What does a percent yield of 95% tell a chemist?
- 5% of the expected product was lost or not formed (Correct answer)
- The reaction was 5% complete
- 95% of reactants were left over
- The limiting reagent was 95% consumed
Correct answer: 5% of the expected product was lost or not formed
A 95% yield means 5% of the theoretical product was lost, which is a very good result in synthetic chemistry.
Question 3: If 3.6 g of product is collected from a reaction with a theoretical yield of 4.0 g, what is the percent yield?
- 90% (Correct answer)
- 80%
- 111%
- 36%
Correct answer: 90%
(3.6 / 4.0) × 100% = 90% yield.
Question 4: In industrial chemistry, why is maximizing percent yield important?
- It reduces waste and lowers production costs per unit of product (Correct answer)
- It increases the boiling point of the product
- It decreases the activation energy of the reaction
- It eliminates the need for a limiting reagent
Correct answer: It reduces waste and lowers production costs per unit of product
Higher percent yield means less raw material is wasted and more product is obtained per run, directly reducing manufacturing costs.
Question 5: What is the theoretical yield if the actual yield is 12 g and the percent yield is 60%?
- 20 g (Correct answer)
- 7.2 g
- 72 g
- 0.05 g
Correct answer: 20 g
Theoretical yield = actual yield / (percent yield / 100) = 12 / 0.60 = 20 g.
Question 6: Two students run the same reaction. Student A gets 85% yield; Student B gets 91% yield. What does this suggest?
- Student B had less product loss or better technique (Correct answer)
- Student B started with more limiting reagent
- Student A used a different balanced equation
- Student B's theoretical yield was lower
Correct answer: Student B had less product loss or better technique
Higher percent yield from the same reaction indicates Student B recovered more of the possible product, suggesting better lab technique or fewer losses.
RPAL Percent Yield 2
A reaction has a theoretical yield of 25 g and a percent yield of 72%.
What is the actual yield?