Reaction Mechanisms - AP Chemistry

Card 0 of 15

Question

Which of the following is true?

Answer

All of the above describe elementary reactions and how they give an overall mechanism.

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Question

A possible mechanism for the overall reaction Br2 (g) + 2 NO (g) -> 2 NOBr(g) is

02

The rate law for the formation of NOBr based on this mechanism is rate = .

Answer

Based on the slowest step the rate law would be: Rate = k2 \[NOBr2\] \[NO\], but one cannot have a rate law in terms of an intermediate (NOBr2).

Because the first reaction is at equilibrium the rate in the forward direction is equal to that in the reverse, thus:

and:

Substitution yields:

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Question

For the reaction NO2 (g) + CO (g) -> NO (g) + CO2 (g), the reaction was experimentally determined to be Rate = k\[NO2\]2. If the reaction has the following mechanism, what is the rate limiting step, and why?

Step 1: 2 NO2 -> NO3 + NO (slow)

Step 2: NO3 + CO -> NO2 + CO2 (fast)

Answer

The reaction can never go faster than its slowest step.

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Question

04

Based on the figure above, what arrows corresponds to the activation energy of the rate limiting step and the energy of reaction? Is the reaction endo- or exothermic?

Answer

Since the products are higher in energy than the reactions, the reaction is endothermic.

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Question

Consider the following mechanism:

A + B -> R + C (slow)

A + R -> C (fast)

Answer

R is the intermediate. It is formed in Step 1 and consumed in Step 2.

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Question

Which of the following is true?

Answer

All of the above describe elementary reactions and how they give an overall mechanism.

Compare your answer with the correct one above

Question

A possible mechanism for the overall reaction Br2 (g) + 2 NO (g) -> 2 NOBr(g) is

02

The rate law for the formation of NOBr based on this mechanism is rate = .

Answer

Based on the slowest step the rate law would be: Rate = k2 \[NOBr2\] \[NO\], but one cannot have a rate law in terms of an intermediate (NOBr2).

Because the first reaction is at equilibrium the rate in the forward direction is equal to that in the reverse, thus:

and:

Substitution yields:

Compare your answer with the correct one above

Question

For the reaction NO2 (g) + CO (g) -> NO (g) + CO2 (g), the reaction was experimentally determined to be Rate = k\[NO2\]2. If the reaction has the following mechanism, what is the rate limiting step, and why?

Step 1: 2 NO2 -> NO3 + NO (slow)

Step 2: NO3 + CO -> NO2 + CO2 (fast)

Answer

The reaction can never go faster than its slowest step.

Compare your answer with the correct one above

Question

04

Based on the figure above, what arrows corresponds to the activation energy of the rate limiting step and the energy of reaction? Is the reaction endo- or exothermic?

Answer

Since the products are higher in energy than the reactions, the reaction is endothermic.

Compare your answer with the correct one above

Question

Consider the following mechanism:

A + B -> R + C (slow)

A + R -> C (fast)

Answer

R is the intermediate. It is formed in Step 1 and consumed in Step 2.

Compare your answer with the correct one above

Question

Which of the following is true?

Answer

All of the above describe elementary reactions and how they give an overall mechanism.

Compare your answer with the correct one above

Question

A possible mechanism for the overall reaction Br2 (g) + 2 NO (g) -> 2 NOBr(g) is

02

The rate law for the formation of NOBr based on this mechanism is rate = .

Answer

Based on the slowest step the rate law would be: Rate = k2 \[NOBr2\] \[NO\], but one cannot have a rate law in terms of an intermediate (NOBr2).

Because the first reaction is at equilibrium the rate in the forward direction is equal to that in the reverse, thus:

and:

Substitution yields:

Compare your answer with the correct one above

Question

For the reaction NO2 (g) + CO (g) -> NO (g) + CO2 (g), the reaction was experimentally determined to be Rate = k\[NO2\]2. If the reaction has the following mechanism, what is the rate limiting step, and why?

Step 1: 2 NO2 -> NO3 + NO (slow)

Step 2: NO3 + CO -> NO2 + CO2 (fast)

Answer

The reaction can never go faster than its slowest step.

Compare your answer with the correct one above

Question

04

Based on the figure above, what arrows corresponds to the activation energy of the rate limiting step and the energy of reaction? Is the reaction endo- or exothermic?

Answer

Since the products are higher in energy than the reactions, the reaction is endothermic.

Compare your answer with the correct one above

Question

Consider the following mechanism:

A + B -> R + C (slow)

A + R -> C (fast)

Answer

R is the intermediate. It is formed in Step 1 and consumed in Step 2.

Compare your answer with the correct one above

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