Chapter 11, Problem 90QAP

Interpretation Introduction

(a)

Interpretation:

To determine the rate of reaction when 125 mL of water is added.

Concept introduction:

$\text{Concentration}\text{=}\frac{\text{moles}\text{of}\text{solute}}{\text{total}\text{volume}\text{of}\text{solution}}$

When water is added to solution, then total volume of solution increases and thus concentration of reactants decreases as volume is inversely proportional to concentration.

Interpretation Introduction

(b)

Interpretation:

To determine the change in rate constant when temperature is increased.

Concept introduction:

Relation between rate constant and temperature.

$\begin{array}{l}\text{K=}{\text{Ae}}^{\text{-}\frac{{\text{E}}_{\text{a}}}{\text{RT}}}\\ \text{where,}\\ \text{K=}\text{rate}\text{constant}\\ \text{A}\text{=}\text{Arehenius}\text{factor}\\ {\text{E}}_{\text{a}}\text{=}\text{activation}\text{energy}\\ \text{R}\text{=}\text{universal}\text{gas}\text{constant}\\ \text{T}\text{=}\text{Temperature}\end{array}$

Interpretation Introduction

(c)

Interpretation:

To determine the change in activation when HCl is added.

Concept introduction:

Relation between rate constant and temperature.

$\begin{array}{l}\text{K=}{\text{Ae}}^{\text{-}\frac{{\text{E}}_{\text{a}}}{\text{RT}}}\\ \text{where,}\\ \text{K=}\text{rate}\text{constant}\\ \text{A}\text{=}\text{Arehenius}\text{factor}\\ {\text{E}}_{\text{a}}\text{=}\text{activation}\text{energy}\\ \text{R}\text{=}\text{universal}\text{gas}\text{constant}\\ \text{T}\text{=}\text{Temperature}\end{array}$

Activation energy is the amount of energy required to reach the transition state. It is independent of temperature. Generally, catalyst is added to increase or decrease the activation energy.

Interpretation Introduction

(d)

Interpretation:

To determine the change in rate of reaction when NaOH is added.

Concept introduction:

$\text{Concentration}\text{=}\frac{\text{moles}\text{of}\text{solute}}{\text{total}\text{volume}\text{of}\text{solution}}$

When water is added to solution, then total volume of solution increases and thus concentration of reactants decreases as volume is inversely proportional to concentration.

Interpretation Introduction

(e)

Interpretation:

To determine the change in rate constant when catalyst is added.

Concept introduction:

Rate of a chemical reaction: It tells us about the speed at which the reactants are converted into products.

Mathematically, rate of reaction is directly proportional to the product of concentration of each reactant raised to the power equal to their respective order of reaction.

Let’s say we have a reaction:

$\begin{array}{l}\text{aA+bB}\stackrel{}{\to }\text{cC+dD}\\ \text{then,}\\ \text{rate}\text{α}{\text{[A]}}^{\text{a}}{\text{[B]}}^{\text{b}}\\ \Rightarrow \text{rate}{\text{=K}}_{\text{f}}{\text{[A]}}^x{\text{[B]}}^y\\ \text{where}{\text{K}}_{\text{f}}\text{= rate}\text{constant}\\ \text{x and y are order of reaction with respect to A and B }\\ \end{array}$

Relation between rate constant and temperature.

$\begin{array}{l}\text{K=}{\text{Ae}}^{\text{-}\frac{{\text{E}}_{\text{a}}}{\text{RT}}}\\ \text{where,}\\ \text{K=}\text{rate}\text{constant}\\ \text{A}\text{=}\text{Arehenius}\text{factor}\\ {\text{E}}_{\text{a}}\text{=}\text{activation}\text{energy}\\ \text{R}\text{=}\text{universal}\text{gas}\text{constant}\\ \text{T}\text{=}\text{Temperature}\end{array}$