Question

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

• A. Positive work is done by 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 1

Answer: (B), (C)

The correct options are
B

Positive work is done on the ice-water system by the atmosphere

C

The internal energy of the ice-water system increases

There is a decrease in volume during melting on an ice slab at 273K.

Therefore, negative work is done by ice-water system on the

atmosphere or positive work is done on the ice-water system by the

atmosphere. Hence option (b) is correct. Secondly heat is absorbed during

melting (i.e., $△Q$ is positive) and as we have seen, work done by ice-water

system is negative ($△W$ is negative). Therefore, from first law of

thermodynamics $△U=△Q-△W$.

Change in internal energy of ice-water system,\(\triangle U\) will be positive or

internal energy will increase.