Question

The addition of NaOH to \[C{{H}_{3}}COOH\] solution shows a decrease in the conductance of the solution.
(A) True
(B) False

Answer 1

Hint: The electrolytic conductance of an electrolyte solution is a measure of its ions carrying capacity which determines the total ionic strength of the solution. This property will be observed when a voltage is applied to the electrodes dipped into an electrolyte solution, then the ions of the electrolyte moves and electric current flow through the electrolytic solution.

Complete step by step solution:
According to Kohlrausch’s law, the conductance of an electrolyte depends on the strength of the electrolyte. It means strong electrolyte has more conductance due to it dissociates completely into ions.
Incase weak electrolyte solutions, it does not dissociation into ions completely indicates less current flow in the solution, which causes less conductance.
All strong acids (like HCl, etc.) and strong bases ( like NaOH, etc.) are strong electrolytes.
All weak acids like $C{{H}_{3}}COOH$ and weak bases like \[N{{H}_{4}}OH\] are weak electrolytes.
i.e, $C{{H}_{3}}COOH\rightleftharpoons C{{H}_{3}}CO{{O}^{-}}+{{H}^{+}}$ -- (1)
when NaOH is added to acetic acid, initially the conductance is low due to the unfeasible ionization of acetic acid. (from equation -1). NaOH is a strong base that dissociates completely into ions.
$NaOH\to N{{a}^{+}}+O{{H}^{-}}$
On the addition fo a strong base like NaOH, there is a decrease in conductance due to the replacement of ${{H}^{+}}$ by $N{{a}^{+}}$ and also decreases the dissociation of acetic acid due to the common ion effect.

Hence, the given statement is true. (option A)

Note: The common ion effect describes the effect on equilibrium involving a substance that adds the same ion as part of the equilibrium. For example, adding common ion prevents weak acid or weak base from ionizing as much as without adding common ion. The common ion effect decreases the ionization of weak acid by adding more ion toward the equilibrium.