Chapter 15 Multiple choice questions

. This question examines the link between statistical thermodynamics and chemical kinetics.
The Arrhenius equation for the forwards rate of a reaction is given as

, where

is the activation energy, the energy difference between the reactants and the transition state, which lies on the reaction path between reactants and products.
The equivalent rate for the backwards reaction (i.e. the one converting products back into reactants) is given as

.
The equilibrium constant,

can be viewed as

,
i.e. the ratio of the forward rate of a reaction to its backwards rate.
Which one of the following statements is always true?

The constants A_fand A_b are related to the entropy of the reactants and of the products, respectively.

The constants A_f and A_b are always the same.

The ratio of A_f and A_b is equal to the ratio of the molecular partition functions of reactants to those of products.

The ratio of A_f to A_b is equal to the ratio of the molecular partition functions of products to those of reactants.

. This question explores the relationship between modern statistical thermodynamics and historical principles such as that of Le Chatelier.
All reactions discussed below involve only gaseous participants.
Consider Eq. 15.11:

Which one of the following statements is true?

In a reaction of the type A₂ → 2A the reaction always follows Le Chatelier's principle.

In an exothermic reaction of the type A + B → 2C + D, the reaction always follows Le Chatelier's principle

In an endothermic reaction of the type A + 2B → C + D, the reaction always follows Le Chatelier's principle.

In a thermoneutral reaction of the type A + B → C + D, the reaction always follows Le Chatelier's principle.