Question 1

Which reaction is fast and has K_eq = 1?

Accepted Answer

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Question 2

How many transition states and intermediates would the reaction profile have for the reaction shown below?

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Question 3

How many transition states are present in the reaction in the energy diagram?

Accepted Answer

There are two transition states present in the reaction, marked by the peaks in the energy diagram. Therefore, the correct answer is C, which indicates that there are two transition states in the reaction.

Question 4

Which reaction is slowest?

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Question 5

Which of the following reaction quantities will have an effect on reaction rate?

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Question 6

Calculate E_a for the conversion of C B.

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Question 7

Which of the following statements is true?

Accepted Answer

A rate equation only contains concentration terms for the reactants involved in the rate-determining step of a reaction mechanism. In a one-step mechanism, all reactants are involved in the rate-determining step, so the rate equation would contain concentration terms for all reactants. In a multi-step mechanism, only the reactants involved in the rate-determining step would be included in the rate equation. Therefore, option C is the correct statement. Option A and B are false statements, and option D is partially true but not as accurate as option C.

Question 8

Which of the following letters represents DH° for the forward reaction in the following energy diagram?

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Question 9

Which compound would you predict to be highest in energy?

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Question 10

The DG° (free energy change) for the conversion of A to B is predicted to be which of the following?

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Question 11

Which of the following statements about enzymes is true?

Accepted Answer

Enzymes lower the activation energy and specifically the transition state for the rate-determining step, making the reaction easier to proceed. None of the other choices are true.

Question 12

What is the name given to the reaction species that lies at an energy minimum between steps on a reaction energy diagram?

Accepted Answer

A reactive intermediate is a species that exists at an energy minimum between steps in a reaction energy diagram, indicating it is stable enough to be detected but not as stable as the final products.

Question 13

Which reaction has a positive DG°, assuming that entropy changes are negligible compared to enthalpy changes?

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Question 14

Which of the following statements about a catalyst is true?

Accepted Answer

A catalyst speeds up a reaction by lowering the energy of activation required for the reaction to occur. This allows more particles to have sufficient energy to react, increasing the rate of the reaction without affecting the equilibrium constant. Therefore, statements A, C, and D are incorrect.

Question 15

In which reaction is K_eq > 1?

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Question 16

Which step would most likely have the largest energy of activation?

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Question 17

Which of the following statements about a two-step reaction mechanism is true?

Accepted Answer

Each step in a two-step reaction mechanism has its own distinct activation energy and enthalpy change, reflecting the individual characteristics and requirements of that step.

Question 18

What kind of reaction does the conversion of A to D represent?

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Question 19

A decrease in which of the following results in an increase in the rate of a chemical reaction?

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Question 20

If the conversion of A to B is slow and B to C is fast, what is the rate equation for this reaction?

Accepted Answer

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Quiz 6: Understanding Organic Reactions

Which reaction is fast and has Keq = 1?