Question

The \(\left(\frac{\partial E}{\partial T}\right)_p\) of different types of half cells are as follows:

A	B	C	D
1 × 10-4	2 × 10-4	0.1 × 10-4	0.2 × 10-4

(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
• D. D

Answer 1

The Correct Option is C

To determine which of the half cells should be used as a reference electrode, we need to consider the value of \(\left(\frac{\partial E}{\partial T}\right)_p\), which represents the rate of change of the electromotive force (E) of the cell with temperature at constant pressure.

When choosing a reference electrode, we prefer one with the least variability in electromotive force with temperature changes. This stability ensures that the reference electrode maintains a consistent potential under varying conditions.

Let's evaluate the given options:

1. For half cell A, \(\left(\frac{\partial E}{\partial T}\right)_p = 1 \times 10^{-4}\)
2. For half cell B, \(\left(\frac{\partial E}{\partial T}\right)_p = 2 \times 10^{-4}\)
3. For half cell C, \(\left(\frac{\partial E}{\partial T}\right)_p = 0.1 \times 10^{-4}\)
4. For half cell D, \(\left(\frac{\partial E}{\partial T}\right)_p = 0.2 \times 10^{-4}\)

From these values, half cell C has the smallest change in electromotive force with temperature, with a value of 0.1 \times 10^{-4}. Hence, it is the most stable option and the best choice as a reference electrode.

Therefore, the correct choice is half cell C.