Question 1

Which of the following statements best describes the significance of the highest point on a reaction coordinate diagram?

Accepted Answer

It is the transition state, representing the highest energy barrier that must be overcome for the reaction to proceed.

Question 2

Given the reaction $$A + B \rightleftharpoons C + D$$, which expression correctly represents the equilibrium constant $$K_{eq}$$?

Accepted Answer

$$K_{eq} = \frac{[C][D]}{[A][B]}$$

Question 3

Which of the following changes will make the Gibbs free energy change ($$\Delta G^\circ) of a $$reaction more negative, thus favoring product formation?

Accepted Answer

Decreasing the enthalpy ($$\Delta H^\circ) $$and increasing the entropy ($$\Delta S^\circ).$$

Question 4

A reaction has $$\Delta H^\circ  0. $$What can be said about the spontaneity of this reaction under standard conditions?

Accepted Answer

The reaction is spontaneous at all temperatures.

Question 5

Which of the following best explains why adding a catalyst increases the rate of a chemical reaction?

Accepted Answer

It lowers the activation energy ($$E_a) $$required for the reaction to proceed.

Question 6

Consider a reaction where the products have more freedom of movement than the reactants. What is the sign of $$\Delta S^\circ$$ for this reaction?

Accepted Answer

$$\Delta S^\circ is $$positive.

Question 7

Which of the following is true about the effect of temperature on the rate constant $$k$$ according to the Arrhenius equation $$k = Ae$$^{-E_a/RT}$$?

Accepted Answer

Increasing temperature increases the rate constant $$k.$$

Question 8

A reaction is said to be exergonic if:

Accepted Answer

$$\Delta G^\circ is $$negative and products are more stable than reactants.

Question 9

Which of the following scenarios will result in a negative $$\Delta H^\circ ($$exothermic reaction)?

Accepted Answer

Bonds formed are stronger than bonds broken.

Question 10

If a reaction has a large activation energy ($$E_a$$), what can be said about its rate?

Accepted Answer

The reaction will occur slowly.

Question 11

Which of the following is NOT a way to increase the rate of a chemical reaction?

Accepted Answer

Decrease the surface area of reactants.

Question 12

In a metabolic pathway, an endergonic reaction is often coupled with an exergonic reaction. What is the purpose of this coupling?

Accepted Answer

To make the overall process thermodynamically favorable.

Question 13

Which of the following statements about catalysts is correct?

Accepted Answer

Catalysts lower the activation energy and are not consumed in the reaction.

Question 14

If a reaction has $$K_{eq} \u003c 1$$, what does this indicate about the relative stability of reactants and products?

Accepted Answer

Reactants are more stable than products.

Question 15

Which of the following best describes the effect of increasing the concentration of reactants on the rate of a chemical reaction?

Accepted Answer

It increases the rate by increasing the frequency of effective collisions.

Question 16

Which equation correctly relates Gibbs free energy change to the equilibrium constant?

Accepted Answer

$$\Delta G^\circ = -RT \ln K_{eq}$$

Question 17

Which of the following is true about entropy ($$\Delta S^\circ) in a $$reaction where the number of product molecules is greater than the number of reactant molecules?

Accepted Answer

$$\Delta S^\circ is $$positive because there is more disorder.

Question 18

Which of the following best describes the transition state in a chemical reaction?

Accepted Answer

It is a temporary, high-energy complex formed at the peak of the energy barrier.

Question 19

Which of the following statements about the effect of strain (torsion, steric, angle) on enthalpy ($$\Delta H^\circ) is $$correct?

Accepted Answer

More strain leads to higher enthalpy.

Question 20

Which of the following is a correct application of Le Châtelier’s principle in chemical reactions?

Accepted Answer

If equilibrium is disrupted, the system will shift to offset the disturbance.

Chapter 5: Chemical Reaction Analysis – Thermodynamics and Kinetics in Organic Chemistry

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