Chapter 17, Problem 17.83P

(a)

Interpretation Introduction

Interpretation:

The given reaction is

  ${\text{X}}_{\text{2(g)}}{\text{+ Y}}_{\text{2(g)}}\rightleftharpoons {\text{2XY}}_{\text{(g)}}$

The reaction quotient, $Q$, for the given reaction has to be written.

Concept Introduction:

Reaction quotient:

The ratio of concentration terms for a reaction is known as reaction quotient.  It is denoted by $Q$.  For a reversible reaction of ${\text{N}}_{\text{2}}{\text{O}}_{\text{4}}{\text{ to NO}}_{\text{2}}$, the reaction quotient is represented as

  $\begin{array}{l}{\text{N}}_{\text{2}}{\text{O}}_{\text{4}\left(\text{g}\right)}\rightleftharpoons {\text{2NO}}_{\text{2(g)}}\\ \\ Q\text{ = }\frac{{\left({\text{NO}}_{\text{2}}\right)}^{\text{2}}}{\left({\text{N}}_{\text{2}}{\text{O}}_{\text{4}}\right)}\end{array}$

(b)

Interpretation Introduction

Interpretation:

The given filmstrip contains five molecular scenes of a gaseous mixture as it reaches equilibrium over time.  In the filmstrip, $\text{X}$ is purple and $\text{Y}$ is orange.

Figure 1

If each particle represents $\text{0}\text{.1 mol}$, $Q$ has to be found for each scene.

Concept Introduction:

Reaction quotient:

The ratio of concentration terms for a reaction is known as reaction quotient.  It is denoted by $Q$.  For a reversible reaction of ${\text{N}}_{\text{2}}{\text{O}}_{\text{4}}{\text{ to NO}}_{\text{2}}$, the reaction quotient is represented as

  $\begin{array}{l}{\text{N}}_{\text{2}}{\text{O}}_{\text{4}\left(\text{g}\right)}\rightleftharpoons {\text{2NO}}_{\text{2(g)}}\\ \\ Q\text{ = }\frac{{\left({\text{NO}}_{\text{2}}\right)}^{\text{2}}}{\left({\text{N}}_{\text{2}}{\text{O}}_{\text{4}}\right)}\end{array}$

(c)

Interpretation Introduction

Interpretation:

The given reaction is

  ${\text{X}}_{\text{2(g)}}{\text{+ Y}}_{\text{2(g)}}\rightleftharpoons {\text{2XY}}_{\text{(g)}}$

If $\text{K > 1}$, the time progressing to the right or to the left has to be explained.

Concept Introduction:

At equilibrium, $Q\text{ = K}$.

If $Q\text{ = K}$, the mixture is at equilibrium.

If $Q\text{ > K}$, the reaction proceeds towards reactants.

If $Q\text{ < K}$, the reaction proceeds towards products.

(d)

Interpretation Introduction

Interpretation:

The given reaction is

  ${\text{X}}_{\text{2(g)}}{\text{+ Y}}_{\text{2(g)}}\rightleftharpoons {\text{2XY}}_{\text{(g)}}$

The value of $\text{K}$ has to be calculated at this temperature.

Concept Introduction:

Reaction quotient:

The ratio of concentration terms for a reaction is known as reaction quotient.  It is denoted by $Q$.  For a reversible reaction of ${\text{N}}_{\text{2}}{\text{O}}_{\text{4}}{\text{ to NO}}_{\text{2}}$, the reaction quotient is represented as

  $\begin{array}{l}{\text{N}}_{\text{2}}{\text{O}}_{\text{4}\left(\text{g}\right)}\rightleftharpoons {\text{2NO}}_{\text{2(g)}}\\ \\ Q\text{ = }\frac{{\left({\text{NO}}_{\text{2}}\right)}^{\text{2}}}{\left({\text{N}}_{\text{2}}{\text{O}}_{\text{4}}\right)}\end{array}$

At equilibrium, $Q\text{ = K}$.

(e)

Interpretation Introduction

Interpretation:

The given filmstrip contains five molecular scenes of a gaseous mixture as it reaches equilibrium over time.  In the filmstrip, $\text{X}$ is purple and $\text{Y}$ is orange.

Figure 1

If ${\text{ΔH}}_{\text{r×n}}^{\text{°}}\text{< 0}$, the scene that represents the mixture at a higher temperature has to be explained.

Concept Introduction:

Change in equilibrium due to temperature changes:

If the temperature is increased for the system, the equilibrium shifts away from the heat because of the reaction needs extra heat to use.

If the temperature is decreased for the system, the equilibrium shifts towards the heat because the heat needs to be produced to make up for the loss.

(f)

Interpretation Introduction

Interpretation:

The given filmstrip contains five molecular scenes of a gaseous mixture as it reaches equilibrium over time.  In the filmstrip, $\text{X}$ is purple and $\text{Y}$ is orange.

Figure 1

The scene that represents the mixture at a higher pressure (lower volume) has to be explained.

Concept Introduction:

Change in equilibrium due to pressure changes:

On increase in the system pressure, the equilibrium shifts towards fewer moles of gas, because, for gases,

  $\text{increase in pressure = decrease in volume}\text{.}$

On decrease in the system pressure, the equilibrium shifts towards more moles of gas, because, for gases,

  $\text{decrease in pressure = increase in volume}\text{.}$