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Study Quiz 3
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1
Which of the following statements is true?
A)Actual yield is a calculated quantity.
B)Actual yield is a measured quantity.
C)Theoretical yield is a measured quantity.
D)None of the above.
2
The actual yield of a chemical reaction is
A)usually less than the theoretical yield
B)usually the same as the theoretical yield
C)usually more than the theoretical yield
D)Determined in advance of doing the experiment
3
In order to determine the percentage yield of a reaction you must
A)calculate the theoretical yield
B)do the reaction
C)measure the amount of product formed
D)all of the above
4
Which of the following is usually not a source of a reduced actual yield?
A)Impure reactants.
B)Poor technique
C)Good experimental design
D)Presence of a competing reaction.
5
A chemist prepares 8.62 g of aspirin in an esterification reaction. She calculated that she would produce 12.1 g in the reaction. What is the percentage yield?
A)140%
B)71.2%
C)1.40%
D).712%
6
A student calculates that he can produce 1.67 g of NaCl by combining 2.40 g of NaHCO3 with HCl(aq). He does the reaction and recovers 1.54 g of NaCl by the evaporation of water. What is the actual yield of the experiment?
A)92.2%
B)2.40 g
C)1.67 g
D)1.54 g
7
A product of an experiment is recovered by evaporating water from a solution. The percentage yield is calculated to be greater than 100%. What could a possible explanation be for this result?
A)A competing reaction decreased the amount of product formed.
B)The mixture was heated too long and too much water evaporated.
C)The mixture was not heated long enough and not all the water evaporated.
D)Some of the product was lost during the heating process.
8
Percentage purity of a substance
A)describes what proportion by mass of a sample is composed of a specific substance
B)is always 100% for chemicals used in the lab
C)has no bearing on the percentage yield obtained in a reaction
D)is not affected by the conditions of storage of the substance
9
A chemist believes that a reactant is 100% pure but in fact it is only 80% pure. How will this affect his experiment?
A)More product than expected will be formed.
B)The percentage yield will be lower than expected.
C)The actual yield will be greater than the theoretical yield.
D)There will be no effect on the experiment.





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