The equivalent conductances of two strong electrolytes at infinite dilution in $\mathrm{H}_{2}\mathrm{O}$ (where ions move freely through a solution) at $25^{\circ}\mathrm{C}$ are given below: \[ \begin{aligned} & \wedge_{\mathrm{CH}_{3}\mathrm{COONa}}=91.0 \mathrm{~S} \mathrm{~cm}^{2} / \text { equiv } \\ & \wedge_{\mathrm{HCl}}^{\circ}=426.2 \mathrm{~S} \mathrm{~cm}^{2} / \text { equiv } \end{aligned} \] What additional information/quantity one needs to calculate $\wedge^{\circ}$ of an aqueous solution of acetic acid?

(B) $\wedge^{\circ}$ of $\mathrm{CH}_{3}\mathrm{COOK}$

(C) The limiting equivalent conductance of $\mathrm{H}^{+}\left(\wedge_{\mathrm{H}^{+}}^{\circ}\right)$

(D) $\wedge^{\circ}$ of chloroacetic acid $\left(\mathrm{C}/\mathrm{CH}_{2}\mathrm{COOH}\right)$

JEE Main · 2007 · 29 Apr 2007 · Offline · Redox Reactions and Electrochemistry

The equivalent conductances of two strong electrolytes at infinite dilution in

H_{2} O

(where ions move freely through a solution) at

2 5^{\circ} C

are given below:

\land_{CH_{3} COONa} = 91.0 S cm^{2} / equiv \land_{HCl}^{\circ} = 426.2 S cm^{2} / equiv

What additional information/quantity one needs to calculate

\land^{\circ}

of an aqueous solution of acetic acid?

(A) $\land^{\circ}$ of NaCl✓ Correct
(B) $\land^{\circ}$ of $CH_{3} COOK$
(C)The limiting equivalent conductance of $H^{+} (\land_{H^{+}}^{\circ})$
(D) $\land^{\circ}$ of chloroacetic acid $(C / CH_{2} COOH)$

Answer: (A)

Solution

Kohlrausch's law lets the limiting molar conductivity of acetic acid be assembled from strong-electrolyte values as

Λ_{C H_{3} COOH}^{\circ} = Λ_{C H_{3} COONa}^{\circ} + Λ_{HCl}^{\circ} - Λ_{NaCl}^{\circ}

. The sodium-acetate and hydrochloric-acid values are already supplied, so the one further quantity needed to complete the sum is the limiting conductivity of sodium chloride.

JEE Main · 2007 · 29 Apr 2007 · Offline · Single correct option

Practise more: all JEE Main PYQs on Redox Reactions and Electrochemistry →

JEE Main · 2007 · 29 Apr 2007 · Offline · Redox Reactions and Electrochemistry

Solution

More JEE Main questions on Redox Reactions and Electrochemistry