NEET levelSingle correct optionDifficulty 1 of 3ec056
A cell reaction involving 2 electrons has (∂T∂E∘)P=2.0×10−4VK−1. Taking F=96500Cmol−1, ΔrS∘ is
A38.6JK−1mol−1
B19.3JK−1mol−1
C77.2JK−1mol−1
D−38.6JK−1mol−1
Answer: A
ΔrS∘=nF(∂T∂E∘)P=2×96500×2.0×10−4=38.6JK−1mol−1. The sign follows the sign of the temperature coefficient, so a positive coefficient gives positive entropy change. Option B forgets n.