Question

1 mole of an ideal gas is allowed to expand isothermally and reversibly from 1L to 5L at 300 K. The change in enthalpy (in kJ) is
(R = 8.3 J K\(^{-1}\) mol\(^{-1}\))

• A. 1.74
• B. 2.48
• C. 0.0
• D. 4.22

Hint:

In isothermal processes, the temperature of the system remains constant. Therefore, the change in internal energy \(\Delta U = 0\) and the change in enthalpy \(\Delta H = 0\) for an ideal gas.

Answer 1

The Correct Option is C

Step 1: Use the formula for change in enthalpy
For an ideal gas undergoing an isothermal process: \[ \Delta H = nC_p\Delta T \] But since the process is isothermal (\(\Delta T = 0\)): \[ \Delta H = 0 \] Step 2: Conclusion
Since the temperature remains constant throughout the isothermal expansion, the change in enthalpy is zero.