Chapter 19, Problem 92A

Interpretation Introduction

Interpretation : The addition of hydrochloric acid that affects the equilibrium between the hypochlorous acid and the hypochlorite ion is to be explained.

Concept Introduction : Acids are substances that contain hydrogen and ionize to produce hydrogen ions $\left({\text{H}}^{\text{+}}\right)$ in an aqueous solution.

Answer to Problem 92A

The addition of hydrochloric acid shifts the equilibrium towards the left of the reaction.

Explanation of Solution

The equilibrium that exists between the hypochlorous acid and the hypochlorite ion is given as

  $\text{HOCl}\left(aq\right)+{\text{OH}}^{-}\left(aq\right)\rightleftharpoons {\text{OCl}}^{-}\left(aq\right)+{\text{H}}_{\text{2}}\text{O}\left(l\right)$

  $\text{HCl}$ is added to the above equation, $\text{HCl}$ being the strong acid so it facilitates the reaction toward the hydroxide ion. There is an excess of ${\text{H}}^{+}$ ions absorbed. So, the equation is shifted towards the left.

Interpretation Introduction

Interpretation : The addition of sodium hydroxide that affects the equilibrium between the hypochlorous acid and the hypochlorite ion is to be explained.

Concept Introduction : Bases are substances that ionize in aqueous solutions to produce hydroxide ions $\left({\text{OH}}^{-}\right)$ .

Answer to Problem 92A

The addition of sodium hydroxide shifts the equilibrium towards the right of the reaction.

Explanation of Solution

The equilibrium that exists between the hypochlorous acid and the hypochlorite ion is given as

  $\text{HOCl}\left(aq\right)+{\text{OH}}^{-}\left(aq\right)\rightleftharpoons {\text{OCl}}^{-}\left(aq\right)+{\text{H}}_{\text{2}}\text{O}\left(l\right)$

  $\text{NaOH}$ is added to the above equation, $\text{NaOH}$ being the strong bases so there were more hydroxide ions are formed since the reactants are more. There is formation of more products. So, the equation is shifted towards the right.