Question

During an isothermal expansion, a confined ideal gas does –150 J of work against its surroundings. This implies that

Answer 1

Given : During an isothermal expansion, a confined ideal gas does –150 J of work against its surroundings.

To check : The implies that ...

A. 300 J of heat has been added to the gas.

B. no hear is transferred because the process is isothermal.

C. 150J of heat has been added to the gas.

D. 150 J of heat has been removed from the gas.

solution : the process is an isothermal expansion.

so, ∆U = 0

from first law of thermodynamics,

Q = ∆U + w

⇒Q = w = - 150 J

[ negative work done implies that work is done on the system and negative heat implies that heat is added to the system ]

so, 150 J of heat has been added to the gas.

Therefore option (C) is correct choice.