Question
During an isothermal expansion, a confined ideal gas does - 150 J of work against its surroundings. This implies that
-
300 J of heat has been added to the gas
-
no heat is transferred because the process is isothermal
-
150 J of heat has been added to the gas
-
150 J of heat has been removed from the gas
Solution
C.
150 J of heat has been added to the gas
From the first law of thermodynamics
ΔU = Q + W
For isothermal process, ΔU = 0
therefore, Q = - W
Given W = - 150
Therefore, Q = + 150
When Q is positive, the heat is added to the gas.
