Chapter 12, Problem 1E

(a)

Summary Introduction

To calculate: The rate constant for the nonenzymatic elementary reaction AàB.

Concept introduction: The rate constant is the proportionality constant in an elementary reaction. The rate constant helps to quantify the rate of the reaction.

Explanation of Solution

Calculation:

Given:

The nonenzymatic elementary reaction is AàB, where A is the reactant and B is the product.

The concentration of A = 20mM

The reaction velocity = 5µm of B/minute

The velocity of an instantaneous reaction is $v=k[\text{A}]$

where,

 v is the reaction velocity

 k is the reaction constant

 [A] is the concentration of A

The given values are substituted in the following rearranged equation for velocity of an instantaneous reaction,

$\begin{array}{c}k=\frac{v}{[\text{A}]}\\ =\frac{\text{5μM}{\text{min}}^{\text{-1}}}{\text{20mM}}\\ =\frac{{\text{5×10}}^{\text{-3}}\text{mM}{\text{min}}^{\text{-1}}}{\text{20mM}}\\ =2.5\times {\text{10}}^{\text{-4}}{\text{min}}^{\text{-1}}\end{array}$

  

Conclusion

Conclusion: The rate constant for the nonenzymatic elementary reaction AàB is

2.5×10^-4 min^-1.

(b)

Summary Introduction

To determine: The molecularity of the given nonenzymatic elementary reaction AàB

Concept introduction: Molecularity of elementary reaction is defined as the total number of molecules or ions in the reaction that participate in the rate determining step.

Explanation of Solution

Explanation: In the given reaction, there is only one rate determining step. Here, only one molecule of A is participating in the rate determining step. Therefore, molecularity is one.

Conclusion

Conclusion: The molecularity of the given nonenzymatic elementary reaction AàB is 1.