Lesson 5.3.1
5.3.1 Percentage error, percentage yield and atom economy Quiz: Pearson Edexcel Chemistry, Unit 5
20 questions
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Lesson 5.3.1, Percentage error, percentage yield and atom economy: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 5: Formulae, Equations and Amounts of Substance, written with Revision Ninja.
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The 20 questions
-
Which ratio is multiplied by 100 to determine percentage yield?
- Theoretical to actual
- Actual to theoretical
- Reactant to product
- Useful to total
-
A reaction has a theoretical yield of 8.0 g and produces 6.0 g. What is the percentage yield?
- 75%
- 133%
- 80%
- 60%
-
A volume of 25.0 cm3 is measured with an uncertainty of plus or minus 0.05 cm3. What is the percentage uncertainty?
- 0.2%
- 0.05%
- 2%
- 0.02%
-
A mass of 0.50 g is measured to plus or minus 0.01 g. What is the percentage uncertainty?
- 0.02%
- 2%
- 0.2%
- 5%
-
How can a student reduce the percentage uncertainty of a titration reading?
- Add more indicator
- Increase titre volume
- Decrease titre volume
- Use smaller flask
-
What technique is used to reduce the impact of random errors in experiments?
- Zeroing the balance
- Calibrating equipment
- Using pure reagents
- Calculating a mean
-
Which situation is an example of a systematic error?
- Parallax reading variation
- Incorrect balance calibration
- Fluctuating room temperature
- Human reaction delay
-
Which factor leads to a percentage yield of less than 100%?
- Incomplete reaction
- Wet product sample
- Impurities in product
- Overestimated reactant mass
-
What does the atom economy of a reaction measure?
- Overall reaction rate
- Product mass yield
- Activation energy barrier
- Reactant atom efficiency
-
A reaction theoretically gives 0.50 mol of product and actually gives 0.40 mol. What is the percentage yield?
- 125%
- 40%
- 20%
- 80%
-
10.0 g of calcium carbonate is heated and gives 4.0 g of calcium oxide. What is the percentage yield? (CaCO3 = 100, CaO = 56)
- 56%
- 40%
- 100%
- 71%
-
A student measures a titre of 24.50 cm3, but the true value is 25.00 cm3. What is the percentage error?
- 24.5%
- 0.5%
- 4.0%
- 2.0%
-
A two-step synthesis has yields of 80% and 65%. What is the overall percentage yield?
- 65%
- 145%
- 72.5%
- 52%
-
How can the percentage uncertainty of a mass measurement be reduced?
- Use larger beaker
- Weigh smaller mass
- Weigh larger mass
- Tare balance twice
-
What causes a calculated percentage yield to exceed 100%?
- Unwanted side reactions
- Incomplete chemical reaction
- Impure damp product
- Loss during filtration
-
What does a low atom economy indicate despite a high percentage yield?
- Reactants are unreacted
- Reaction is incomplete
- Mass is lost
- By-products are formed
-
Which type of error causes measurements to differ unpredictably around the true value?
- Random error
- Calibration error
- Instrumental uncertainty
- Systematic error
-
What type of error is present if results are precise but not accurate?
- Absolute error
- Systematic error
- Random error
- Human error
-
A 2-step synthesis has an overall yield of 50%. The first step has a yield of 100%. What is the yield of the second step?
- 100%
- 50%
- 150%
- 25%
-
Which expression calculates the percentage uncertainty in a measurement?
- (Uncertainty ÷ yield) × 100
- (Reading ÷ uncertainty) × 100
- (Uncertainty ÷ reading) × 100
- (Yield ÷ reading) × 100
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