Chapter 6, Problem 6.76P

Consider the following reaction: $\text{CO}(g)+{\text{CI}}_2(g)\stackrel{}{\rightleftarrows }{\text{ COCI}}_2(g)\text{ with }K=6.6\times {10}^{11}.$

1. Write the expression for the equilibrium constant for this reaction.
2. Are the reactants or products favored at equilibrium?
3. Would you predict $\Delta H$ to be positive or negative?
4. Are the reactants or products lower in energy?
5. Would you predict this reaction to be fast or slow? Explain your choice.

Interpretation Introduction

(a)

Interpretation:

Expression for the equilibrium constant should be written.

Concept Introduction:

The net concentrations of the reactants and products do not change at equilibrium. They are used to define an expression and the equilibrium constant (K) which has a characteristic value.

For a reaction at a given temperature,

  $\text{K=}\frac{\left[\text{Products}\right]}{\left[\text{reactants}\right]}$

Answer to Problem 6.76P

  $\text{K=}\frac{\left[{\text{COCl}}_2\right]}{{\text{[Cl}}_2][\text{CO}]}$

Explanation of Solution

The given equilibrium reaction is represented as follows:

  ${\text{CO(g) + Cl}}_2(g)\rightleftharpoons {\text{COCl}}_2(g)$

The value of equilibrium constant is given as follows:

  $\text{K=6}\text{.6}\times {\text{10}}^{11}$

The expression for the equilibrium constant can be represented as follows:

  $\text{K=}\frac{\left[{\text{COCl}}_2\right]}{{\text{[Cl}}_2][\text{CO}]}$

Interpretation Introduction

(b)

Interpretation:

Whether the reactants or products are favored at the equilibrium should be explained.

Concept Introduction:

The net concentrations of the reactants and products do not change at equilibrium. They are used to define an expression and the equilibrium constant (K) which has a characteristic value.

For a reaction at a given temperature,

  $\text{K=}\frac{\left[\text{Products}\right]}{\left[\text{reactants}\right]}$

Answer to Problem 6.76P

Products are favored in the equilibrium.

Explanation of Solution

The given equilibrium reaction is represented as follows:

  ${\text{CO(g) + Cl}}_2(g)\rightleftharpoons {\text{COCl}}_2(g)$

The value of equilibrium constant is given as follows:

  $\text{K=6}\text{.6}\times {\text{10}}^{11}$

The expression for the equilibrium constant can be represented as follows:

  $\text{K=}\frac{\left[{\text{COCl}}_2\right]}{{\text{[Cl}}_2][\text{CO}]}$

Since, the value of K is too larger (larger than one) products are favored in the given reaction.

Interpretation Introduction

(c)

Interpretation:

Whether the $\Delta$ H should be positive or negative should be determined.

Concept Introduction:

The net concentrations of the reactants and products do not change at equilibrium. They are used to define an expression and the equilibrium constant (K) which has a characteristic value.

For a reaction at a given temperature,

  $\text{K=}\frac{\left[\text{Products}\right]}{\left[\text{reactants}\right]}$

When the K value is less than one, reactants are favored in a reaction.

Answer to Problem 6.76P

  $\Delta$ H is negative.

Explanation of Solution

The given equilibrium reaction is represented as follows:

  ${\text{CO(g) + Cl}}_2(g)\rightleftharpoons {\text{COCl}}_2(g)$

The value of equilibrium constant is given as follows:

  $\text{K=6}\text{.6}\times {\text{10}}^{11}$

The expression for the equilibrium constant can be represented as follows:

  $\text{K=}\frac{\left[{\text{COCl}}_2\right]}{{\text{[Cl}}_2][\text{CO}]}$

The products of a reaction are favored when K is much greater than one (K > 1), and

ΔH is negative. In other words, equilibrium favors the products when they are lower in energy than the reactants.

Interpretation Introduction

(d)

Interpretation:

Whether the reactants or products lower in energy should be determined.

Concept Introduction:

The net concentrations of the reactants and products do not change at equilibrium. They are used to define an expression and the equilibrium constant (K) which has a characteristic value.

For a reaction at a given temperature,

  $\text{K=}\frac{\left[\text{Products}\right]}{\left[\text{reactants}\right]}$

When the K value is less than one, reactants are favored in a reaction.

Answer to Problem 6.76P

Products are lower in energy.

Explanation of Solution

The given equilibrium reaction is represented as follows:

  ${\text{CO(g) + Cl}}_2(g)\rightleftharpoons {\text{COCl}}_2(g)$

The value of equilibrium constant is given as follows:

  $\text{K=6}\text{.6}\times {\text{10}}^{11}$

The expression for the equilibrium constant can be represented as follows:

  $\text{K=}\frac{\left[{\text{COCl}}_2\right]}{{\text{[Cl}}_2][\text{CO}]}$

The products of a reaction are favored when K is much greater than one (K > 1), and

ΔH is negative.

In other words, equilibrium favors the products when they are lower in energy than the reactants.

Interpretation Introduction

(e)

Interpretation:

Whether the reaction is fast or slow should be determined.

Concept Introduction:

The net concentrations of the reactants and products do not change at equilibrium. They are used to define an expression and the equilibrium constant (K) which has a characteristic value.

For a reaction at a given temperature,

  $\text{K=}\frac{\left[\text{Products}\right]}{\left[\text{reactants}\right]}$

When the K value is less than one, reactants are favored in a reaction.

Answer to Problem 6.76P

The rate of the reaction cannot be determined.

Explanation of Solution

The given equilibrium reaction is represented as follows:

  ${\text{CO(g) + Cl}}_2(g)\rightleftharpoons {\text{COCl}}_2(g)$

The value of equilibrium constant is given as follows:

  $\text{K=6}\text{.6}\times {\text{10}}^{11}$

The expression for the equilibrium constant can be represented as follows:

  $\text{K=}\frac{\left[{\text{COCl}}_2\right]}{{\text{[Cl}}_2][\text{CO}]}$

The equilibrium constant (K) has a characteristic value for a reaction at a given temperature.

An idea about reaction rate cannot be made using the value of equilibrium constant.

Rate of reaction do not depend on the value of the equilibrium constant thus, the reaction rate cannot be determined using the equilibrium constant.