During the melting of a slab of ice at 273K at atmospheric pressure,

Options

A. Positive work is done by the ice-water system on the atmosphere
B. Positive work is done on the ice-water system by the atmosphere
C. The internal energy of the ice-water system increases
D. The internal energy of the ice-water system decreases

Answer

B, C

Explanation

There is a decrease in volume during melting of an ice slab at 273 K. Therefore, negative work is done by ice-water system on the atmosphere or positive work is done one the ice-water system by the atmosphere. Hence option (b) is correct. Second, heat is absorbed during melting (i.e., dQ is positive) and as we have seen, work done by ice-water system is negative (dW is negative.) Therefore, from the first law of thermodynamics, with change in internal energy of ice-water system, dU will be positive or internal energy will increase.