JEE Main · 2022 · 26 Jun 2022 · Shift 1 · Redox Reactions and Electrochemistry

The

(\frac{\partial E}{\partial T})_{P}

of four different types of half cells are as follows (in

V K^{- 1}

): A

= 1 \times 1 0^{- 4}

, B

= 2 \times 1 0^{- 4}

, C

= 0.1 \times 1 0^{- 4}

, D

= 0.2 \times 1 0^{- 4}

(where E is the electromotive force). Which of the above half cells would be preferred to be used as reference electrode?

(A)A
(B)B
(C)C✓ Correct
(D)D

Answer: (C)

Solution

A reference electrode is useful only if its potential barely shifts as the temperature changes, so the half cell to pick is the one with the smallest temperature coefficient

(\frac{\partial E}{\partial T})_{P}

. Among the four values the smallest is

0.1 \times 1 0^{- 4} V K^{- 1}

, an order of magnitude below the rest, so that cell holds its emf most steadily over a range of temperatures and is the one preferred as the reference electrode.

JEE Main · 2022 · 26 Jun 2022 · Shift 1 · Single correct option

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JEE Main · 2022 · 26 Jun 2022 · Shift 1 · Redox Reactions and Electrochemistry

Solution

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