Exemplar Problems

Problem 7 : Two moles of an ideal gas undergo an isothermal expansion at 300 K from a volume of 10 liters to 20 liters. Calculate the change in internal energy (∆U) for the process.

Solution :

The change in internal energy (∆U) for an isothermal process involving an ideal gas is given by:

∆U = nCv∆T

Where:

• n is the number of moles of the gas (2 moles in this case).
• Cv is the molar heat capacity at constant volume.
• ∆T is the change in temperature in Kelvin.

Since the process is isothermal, ∆T = 0, which means there is no change in internal energy (∆U) for this process.