**Q1: **

The decomposition of compound A into compounds B and E is a first-order reaction with overall rate constant . The decomposition involves the following four elementary reactions.

- Reaction 1: , rate constant =
- Reaction 2: , rate constant =
- Reaction 3: , rate constant =
- Reaction 4: , rate constant =

The rate law for this reaction is given by

Write a balanced chemical equation for the overall reaction.

In the preequilibrium approximation, the rates of reactions 1 and 2 are equal. Use the preequilibrium approximation to find an expression for in terms of the elementary reaction rate constants.

In the steady-state approximation, the rates of change of [C] and [D] are zero. No assumptions are made regarding [B] or the rates of reactions 1 and 2. Use the steady-state approximation to find an expression for in terms of the elementary reaction rate constants.

Which condition must be satisfied for the preequilibrium and steady-state approximations to produce the same expression for ?

**Q2: **

Compound A decomposes into compounds C, D, and E. The decomposition involves the following three elementary reactions.

- Reaction 1: , rate constant =
- Reaction 2: , rate constant =
- Reaction 3: , rate constant =

The rates of reaction may be estimated by using a steady-state approximation. In this approximation, the rate of change of [B] is zero.

The stoichiometry of the reaction depends on the relative rates of reactions 2 and 3. Based on the mechanism described, which of the following is **not** a balanced reaction equation?

Which condition must be satisfied for the steady-state approximation to be valid?

Use the steady-state approximation to find an expression for the rate of formation of C in terms of [A] and the elementary reaction rate constants.

Use the steady-state approximation to find an expression for the rate of formation of E in terms of [A] and the elementary reaction rate constants.