Chapter 8, Problem 8.53E

Use Le Chȃtelier’s principle to predict the direction of equilibrium shift and the changes that will be observed (color, amount of precipitate, etc.) in the following equilibria when the indicated stress is applied:

a. $\begin{array}{l}\text{heat}+{\text{Co}}^{2+}\left(\text{aq}\right)+4{\text{Cl}}^{-}\left(\text{aq}\right)\rightleftarrows {\text{CoCl}}_4{}^{-}\left(\text{aq}\right);\\ \text{pink}\text{colorless}\text{blue}\end{array}$

The equilibrium mixture is heated.

b. $\begin{array}{l}\text{heat}+{\text{Co}}^{2+}\left(\text{aq}\right)+4{\text{Cl}}^{-}\left(\text{aq}\right)\rightleftarrows {\text{CoCl}}_4{}^{-}\left(\text{aq}\right);\\ \text{pink}\text{colorless}\text{blue}\end{array}$

${\text{Co}}^{2+}$ is added to the equilibrium mixture.

c. $\begin{array}{l}{\text{Fe}}^{3+}\left(\text{aq}\right)+6{\text{SCN}}^{-}\left(\text{aq}\right)\rightleftarrows \text{Fe}{\left(\text{SCN}\right)}_6{}^{3-}\left(\text{aq}\right);\\ \text{brown}\text{colorless}\text{red}\end{array}$

${\text{SCN}}^{-}$ is added to the equilibrium mixture.

d. $\begin{array}{l}{\text{Pb}}^{2+}\left(\text{aq}\right)+2{\text{Cl}}^{-}\left(\text{aq}\right)\rightleftarrows {\text{PbCl}}_2\left(\text{s}\right)+\text{heat};\\ \text{colorless}\text{colorless}\text{white}\text{solid}\end{array}$

${\text{Pb}}^{2+}$ is added to the equilibrium mixture.

e. $\begin{array}{l}{\text{C}}_{\text{2}}{\text{H}}_{\text{4}}+{\text{I}}_{\text{2}}\rightleftarrows {\text{C}}_{\text{2}}{\text{H}}_{\text{4}}{\text{I}}_{\text{2}}+\text{heat};\\ \text{colorless}\text{gas}\text{violet}\text{gas}\text{colorless}\text{gas}\end{array}$

A catalyst is added to the equilibrium mixture.

Interpretation Introduction

(a)

Interpretation:

The direction of the equilibrium shift and the change that will be observed (color, amount of precipitate, etc.) in the given equilibria when the indicated stress is applied is to be predicted using the Le Chȃtelier’s principle.

Concept introduction:

The equilibrium constant is a parameter which describes the relationship between concentration of the reactants and the products at equilibrium stage. Equilibrium constant of a reaction is expressed by the ratio of concentration of product species raised to the power of their stoichiometric coefficients to the concentration of reactant species raised to the power of their stoichiometric coefficients.

Answer to Problem 8.53E

The shift in the equilibrium will be towards the right direction and blue color will be observed due to the formation of cobalt complex.

Explanation of Solution

According to the Le Chȃtelier’s principle the change in concentration, volume, pressure and temperature affects the equilibrium of the reaction.

The given equilibrium reaction is shown below.

$\begin{array}{l}\text{heat}+{\text{Co}}^{2+}\left(\text{aq}\right)+4{\text{Cl}}^{-}\left(\text{aq}\right)\rightleftarrows {\text{CoCl}}_4{}^{-}\left(\text{aq}\right)\\ \text{pink}\text{colorless}\text{blue}\end{array}$

It is considered that when reaction mixture is heated, the temperature on the left hand side increases. Hence, according to the Le Chȃtelier’s principle, the equilibrium will shift towards right direction to compensate the increase in temperature. Thus, blue color will be observed due to the formation of cobalt complex.

Conclusion

The shift in the equilibrium will be towards the right direction and blue color will be observed due to the formation of cobalt complex.

Interpretation Introduction

(b)

Interpretation:

The direction of the equilibrium shift and the change that will be observed (color, amount of precipitate, etc.) in the given equilibria when the indicated stress is applied is to be predicted using the Le Chȃtelier’s principle.

Concept introduction:

The equilibrium constant is a parameter which describes the relationship between concentration of the reactants and the products at equilibrium stage. Equilibrium constant of a reaction is expressed by the ratio of concentration of product species raised to the power of their stoichiometric coefficients to the concentration of reactant species raised to the power of their stoichiometric coefficients.

Answer to Problem 8.53E

The shift in the equilibrium will be towards the right direction and blue color will be observed due to the formation of cobalt complex.

Explanation of Solution

According to the Le Chȃtelier’s principle the change in concentration, volume, pressure and temperature affects the equilibrium of the reaction.

The given equilibrium reaction is shown below.

$\begin{array}{l}\text{heat}+{\text{Co}}^{2+}\left(\text{aq}\right)+4{\text{Cl}}^{-}\left(\text{aq}\right)\rightleftarrows {\text{CoCl}}_4{}^{-}\left(\text{aq}\right)\\ \text{pink}\text{colorless}\text{blue}\end{array}$

It is considered that when ${\text{Co}}^{2+}$ is added to the equilibrium mixture, the amount of ${\text{Co}}^{2+}$ on the left hand side increases. Hence, according to the Le Chȃtelier’s principle, the equilibrium will shift towards right direction to compensate the increased amount of ${\text{Co}}^{2+}$. Thus, blue color will be observed due to the formation of cobalt complex.

Conclusion

The shift in the equilibrium will be towards the right direction and blue color will be observed due to the formation of cobalt complex.

Interpretation Introduction

(c)

Interpretation:

The direction of the equilibrium shift and the change that will be observed (color, amount of precipitate, etc.) in the given equilibria when the indicated stress is applied is to be predicted using the Le Chȃtelier’s principle.

Concept introduction:

The equilibrium constant is a parameter which describes the relationship between concentration of the reactants and the products at equilibrium stage. Equilibrium constant of a reaction is expressed by the ratio of concentration of product species raised to the power of their stoichiometric coefficients to the concentration of reactant species raised to the power of their stoichiometric coefficients.

Answer to Problem 8.53E

The shift in the equilibrium will be towards the right direction and red color will be observed due to the formation of iron complex.

Explanation of Solution

According to the Le Chȃtelier’s principle the change in concentration, volume, pressure and temperature affects the equilibrium of the reaction.

The given equilibrium reaction is shown below.

$\begin{array}{l}{\text{Fe}}^{3+}\left(\text{aq}\right)+6{\text{SCN}}^{-}\left(\text{aq}\right)\rightleftarrows \text{Fe}{\left(\text{SCN}\right)}_6{}^{3-}\left(\text{aq}\right)\\ \text{brown}\text{colorless}\text{red}\end{array}$

It is considered that when ${\text{SCN}}^{-}$ is added to the equilibrium mixture, the amount of ${\text{SCN}}^{-}$ on the left hand side increases. Hence, according to the Le Chȃtelier’s principle, the equilibrium will shift towards right direction to compensate the increased amount of ${\text{SCN}}^{-}$. Thus, red color will be observed due to the formation of iron complex.

Conclusion

The shift in the equilibrium will be towards the right direction and red color will be observed due to the formation of iron complex.

Interpretation Introduction

(d)

Interpretation:

The direction of the equilibrium shift and the change that will be observed (color, amount of precipitate, etc.) in the given equilibria when the indicated stress is applied is to be predicted using the Le Chȃtelier’s principle.

Concept introduction:

The equilibrium constant is a parameter which describes the relationship between concentration of the reactants and the products at equilibrium stage. Equilibrium constant of a reaction is expressed by the ratio of concentration of product species raised to the power of their stoichiometric coefficients to the concentration of reactant species raised to the power of their stoichiometric coefficients.

Answer to Problem 8.53E

The shift in the equilibrium will be towards the right direction and white solid will be formed due to the formation of lead chloride.

Explanation of Solution

According to the Le Chȃtelier’s principle the change in concentration, volume, pressure and temperature affects the equilibrium of the reaction.

The given equilibrium reaction is shown below.

$\begin{array}{l}{\text{Pb}}^{2+}\left(\text{aq}\right)+2{\text{Cl}}^{-}\left(\text{aq}\right)\rightleftarrows {\text{PbCl}}_2\left(\text{s}\right)+\text{heat}\\ \text{colorless}\text{colorless}\text{white}\text{solid}\end{array}$

It is considered that when ${\text{Pb}}^{2+}$ is added to the equilibrium mixture, the amount of ${\text{Pb}}^{2+}$ on the left hand side increases. Hence, according to the Le Chȃtelier’s principle, the equilibrium will shift towards right direction to compensate the increased amount of ${\text{Pb}}^{2+}$. Thus, white solid will be formed due to the formation of lead chloride.

Conclusion

The shift in the equilibrium will be towards the right direction and white solid will be formed due to the formation of lead chloride.

Interpretation Introduction

(e)

Interpretation:

The direction of the equilibrium shift and the change that will be observed (color, amount of precipitate, etc.) in the given equilibria when the indicated stress is applied is to be predicted using the Le Chȃtelier’s principle.

Concept introduction:

The equilibrium constant is a parameter which describes the relationship between concentration of the reactants and the products at equilibrium stage. Equilibrium constant of a reaction is expressed by the ratio of concentration of product species raised to the power of their stoichiometric coefficients to the concentration of reactant species raised to the power of their stoichiometric coefficients.

Answer to Problem 8.53E

There will be no effect of catalyst on the equilibrium of the reaction.

Explanation of Solution

According to the Le Chȃtelier’s principle the change in concentration, volume, pressure and temperature affects the equilibrium of the reaction.

The given equilibrium reaction is shown below.

$\begin{array}{l}{\text{C}}_{\text{2}}{\text{H}}_{\text{4}}+{\text{I}}_{\text{2}}\rightleftarrows {\text{C}}_{\text{2}}{\text{H}}_{\text{4}}{\text{I}}_{\text{2}}+\text{heat}\\ \text{colorless}\text{gas}\text{violet}\text{gas}\text{colorless}\text{gas}\end{array}$

It is considered that when catalyst is added to the equilibrium mixture, there will be no effect of catalyst on the equilibrium. It will only increase the rate of reaction.

Conclusion

There will be no effect of catalyst on the equilibrium of the reaction.