Chapter 5, Problem 5G.12E

(a)

Interpretation Introduction

Interpretation:

The reaction quotient, $\text{Q}$ has to be written for the given reaction:

  ${\text{NCl}}_{\text{3}\left(\text{g}\right)}\text{+}\text{3}{\text{H}}_{\text{2}}{\text{O}}_{\left(\text{l}\right)}\stackrel{}{\to }{\text{NH}}_{\text{3}\left(\text{g}\right)}\text{+}\text{3}\text{HClO}{}_{\left(\text{aq}\right)}$

Concept Introduction:

The reaction quotient, $\text{Q}$, is characteristic of the composition of reaction mixture at equilibrium at a given temperature.

For the reaction,

  $\text{a}{\text{A}}_{\left(\text{g}\right)}\text{+}\text{b}{\text{B}}_{\left(\text{g}\right)}\rightleftharpoons \text{c}{\text{C}}_{\left(\text{g}\right)}\text{+}\text{d}{\text{D}}_{\left(\text{g}\right)}$

The reaction quotient can be written as

  $\text{Q}\text{=}\frac{{\left({\text{a}}_{\text{C}}\right)}^{\text{c}}{\left({\text{a}}_{\text{D}}\right)}^{\text{d}}}{{\left({\text{a}}_{\text{A}}\right)}^{\text{a}}{\left({\text{a}}_{\text{B}}\right)}^{\text{b}}}$

The expression of reaction quotient is same as the equilibrium constant expression, but activities in reaction quotient refers to any stage of the reaction.

Explanation of Solution

Given reaction is

  ${\text{NCl}}_{\text{3}\left(\text{g}\right)}\text{+}\text{3}{\text{H}}_{\text{2}}{\text{O}}_{\left(\text{l}\right)}\stackrel{}{\to }{\text{NH}}_{\text{3}\left(\text{g}\right)}\text{+}\text{3}\text{HClO}{}_{\left(\text{aq}\right)}$

The reaction quotient can be written by taking the activities of products in numerator raised to the power of its stoichiometric coefficient and activities of reactants in the denominator raised to the power of its stoichiometric coefficient.

The solids and liquids which are pure solvents are not included in the expression of reaction quotient as their activity is one.  Hence, ${\text{H}}_{\text{2}}\text{O}$ does not include in the expression of reaction quotient.

The reaction quotient for the given reaction can be written as

  $\text{Q}\text{=}\frac{\left({\text{a}}_{{\text{NH}}_{\text{3}}}\right){\left({\text{a}}_{\text{HClO}}\right)}^{\text{3}}}{\left({\text{a}}_{{\text{NCl}}_{\text{3}}}\right)}\text{=}\frac{\left({\text{P}}_{{\text{NH}}_{\text{3}}}\right){\left({\text{P}}_{\text{HClO}}\right)}^{\text{3}}}{\left({\text{P}}_{{\text{NCl}}_{\text{3}}}\right)}$

(b)

Interpretation Introduction

Interpretation:

The reaction quotient, $\text{Q}$ has to be written for the given reaction:

  ${\text{P}}_{\text{4}\left(\text{s}\right)}\text{+}\text{3}{\text{KOH}}_{\left(\text{aq}\right)}\text{+}\text{3}{\text{H}}_{\text{2}}\text{O}{}_{\left(\text{l}\right)}\stackrel{}{\to }{\text{PH}}_{\text{3}\left(\text{aq}\right)}\text{+}\text{3}{\text{KH}}_{\text{2}}{\text{PO}}_{\text{2}\left(\text{aq}\right)}$

Concept Introduction:

Refer to sub-part (a).

Explanation of Solution

Given reaction is

  ${\text{P}}_{\text{4}\left(\text{s}\right)}\text{+}\text{3}{\text{KOH}}_{\left(\text{aq}\right)}\text{+}\text{3}{\text{H}}_{\text{2}}\text{O}{}_{\left(\text{l}\right)}\stackrel{}{\to }{\text{PH}}_{\text{3}\left(\text{aq}\right)}\text{+}\text{3}{\text{KH}}_{\text{2}}{\text{PO}}_{\text{2}\left(\text{aq}\right)}$

The solids and liquids which are pure solvents are not included in the expression of reaction quotient as their activity is one.  Hence, ${\text{P}}_{\text{4}\left(\text{s}\right)}$ and ${\text{H}}_{\text{2}}{\text{O}}_{\left(\text{l}\right)}$ which is a pure solvent are not mentioned in the expression of reaction quotient.

The reaction quotient for the given reaction can be written as

  $\text{Q}\text{=}\frac{\left({\text{a}}_{{\text{PH}}_{\text{3}}}\right){\left({\text{a}}_{{\text{KH}}_{\text{2}}{\text{PO}}_{\text{2}}}\right)}^{\text{3}}}{{\left({\text{a}}_{\text{KOH}}\right)}^{\text{3}}}\text{=}\frac{\left({\text{P}}_{{\text{PH}}_{\text{3}}}\right){\left({\text{P}}_{{\text{KH}}_{\text{2}}{\text{PO}}_{\text{2}}}\right)}^{\text{3}}}{{\left({\text{P}}_{\text{KOH}}\right)}^{\text{3}}}$

(c)

Interpretation Introduction

Interpretation:

The reaction quotient, $\text{Q}$ has to be written for the given reaction:

  ${\text{CO}}_{\text{3}}^{\text{2-}}{}_{\left(\text{aq}\right)}\text{+}\text{2}{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{}_{\left(\text{aq}\right)}\stackrel{}{\to }{\text{CO}}_{\text{2}\left(\text{g}\right)}\text{+}\text{3}{\text{H}}_{\text{2}}\text{O}{}_{\left(\text{l}\right)}$

Concept Introduction:

Refer to sub-part (a).

Explanation of Solution

Given reaction is

  ${\text{CO}}_{\text{3}}^{\text{2-}}{}_{\left(\text{aq}\right)}\text{+}\text{2}{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{}_{\left(\text{aq}\right)}\stackrel{}{\to }{\text{CO}}_{\text{2}\left(\text{g}\right)}\text{+}\text{3}{\text{H}}_{\text{2}}\text{O}{}_{\left(\text{l}\right)}$

The solids and liquids which are pure solvents are not included in the expression of reaction quotient as their activity is one.  Hence, ${\text{H}}_{\text{2}}{\text{O}}_{\left(\text{l}\right)}$ which is a pure solvent is not mentioned in the expression of reaction quotient.

The reaction quotient for the given reaction can be written as

  $\text{Q}\text{=}\frac{\left({\text{a}}_{{\text{CO}}_{\text{2}}}\right)}{\left({\text{a}}_{{\text{CO}}_{\text{3}}^{\text{2-}}}\right){\left({\text{a}}_{{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}}\right)}^{\text{2}}}\text{=}\frac{\left({\text{P}}_{{\text{CO}}_{\text{2}}}\right)}{\left({\text{P}}_{{\text{CO}}_{\text{3}}^{\text{2-}}}\right){\left({\text{P}}_{{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}}\right)}^{\text{2}}}$