Q: Which equation describes the vibrational frequency ($$\nu) of a $$bond in terms of force constant ($$k_f) $$and reduced mass ($$\mu$$)?

$$\nu = \frac{1}{2\pi} \sqrt{\frac{k_f}{\mu}}$$

Question 1

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

A catalyst increases the rate of a reaction by lowering the activation energy barrier ($$\Delta G$$^{\ddagger}$$) without altering the overall standard Gibbs energy change ($$\Delta G^o$$).

Question 2

In the context of catalysis, what is the 'active site'?

Accepted Answer

The location on the catalyst where reactants interact and the actual chemical transformation occurs, often a metal center.

Question 3

Which equation correctly represents the rate constant ($$k) in $$terms of Gibbs free energy of activation ($$\Delta G$$^{\ddagger}$$)?

Accepted Answer

$$k = \frac{k_b T}{h} \exp\left(-\frac{\Delta G$$^{\ddagger}$$}{RT}\right)$$

Question 4

Which of the following is a key difference between homogeneous and heterogeneous catalysis?

Accepted Answer

Homogeneous catalysis involves reactants, products, and catalyst all in the same phase, while heterogeneous catalysis involves the catalyst in a different phase from the reactants and products.

Question 5

Which of the following is an example of a heterogeneous catalyst?

Accepted Answer

Pd on carbon

Question 6

In a catalytic cycle, what is the 'resting state' of the catalyst?

Accepted Answer

The intermediate with the highest concentration and smallest rate constant, typically at the beginning of the section with the rate-determining step.

Question 7

How can the rate-determining step (RDS) in a catalytic cycle be identified from an energy profile?

Accepted Answer

By finding the largest energy span between a stable intermediate and the next transition state, not necessarily the highest point in the profile.

Question 8

Which process is commonly used to experimentally establish the rate-determining step in a catalytic cycle?

Accepted Answer

Kinetic measurements using spectroscopic techniques to determine rate laws.

Question 9

What is the primary kinetic isotope effect (KIE)?

Accepted Answer

A change in reaction rate when a bond to an isotopomer is broken or formed in the rate-determining step.

Question 10

Which equation describes the vibrational frequency ($$
u) of a $$bond in terms of force constant ($$k_f) $$and reduced mass ($$\mu$$)?

Accepted Answer

$$
u = \frac{1}{2\pi} \sqrt{\frac{k_f}{\mu}}$$

Question 11

What is the effect of additional PPh$$_3 on $$Wilkinson’s catalyst?

Accepted Answer

It hinders the catalyst by affecting the activation pre-equilibrium, reducing the rate of catalysis.

Question 12

Which of the following best describes the principle of microscopic reversibility?

Accepted Answer

The mechanism of the reverse reaction is identical to the forward reaction, including the transition state.

Question 13

What is an 'off-cycle intermediate' in catalysis?

Accepted Answer

A species formed by the catalyst that is inactive and not part of the productive catalytic cycle.

Question 14

Which metric is NOT the best way to assess catalyst performance?

Accepted Answer

Yield

Question 15

In the hydroformylation (oxo process), which catalyst is typically used?

Accepted Answer

[Rh] catalyst

Question 16

Which of the following statements about intermediates in a catalytic cycle is correct?

Accepted Answer

Intermediates are molecular entities formed from starting materials and react further to give products, with a lifetime appreciably longer than a molecular vibration.

Question 17

Which of the following is a common activation route for a pre-catalyst?

Accepted Answer

Loss of a labile ligand

Question 18

What does an inverse kinetic isotope effect ($$\frac{k_H}{k_D} \u003c 1) $$typically indicate?

Accepted Answer

A change in hybridization (e.g., sp$$^2 to sp$^3) in $$the rate-determining step.

Question 19

Which equation describes the reduced mass ($$\mu) of $$two atoms in a bond?

Accepted Answer

$$\mu = \frac{m_1$ m_2$}{m_1$ + m_2$}$$

Fundamentals of Catalysis in Organic Chemistry

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