Introduction:
In thermodynamics, work is defined as the energy transferred to or from a system due to the application of a force over a distance. The work done on a gas during a process can be different for different types of gases, such as ideal gases and van der Waals gases. In an isothermal reversible process, the temperature of the system remains constant, and the process is carried out slowly enough that the system is always in equilibrium with its surroundings. In this context, we will compare the work done by ideal gases and van der Waals gases under isothermal reversible conditions.

Ideal Gas:
An ideal gas is a theoretical gas composed of a large number of identical particles that do not interact with each other. It follows the ideal gas law, which states that the pressure, volume, and temperature of an ideal gas are related by the equation PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

Van der Waals Gas:
A van der Waals gas is a more realistic model of a gas that takes into account intermolecular forces between gas molecules. It is described by the van der Waals equation, which includes corrections for attractive forces (a) and volume occupied by the gas molecules (b). The equation is given by (P + an^2/V^2)(V - nb) = nRT, where a and b are van der Waals constants.

Comparison of Work Done:
Under isothermal reversible conditions, the work done by an ideal gas is greater than that done by a van der Waals gas. This can be understood by considering the differences in the behavior of the two gases.

Expansion Work:
During expansion, both gases do work against an external pressure. However, the ideal gas equation assumes that there are no intermolecular forces, resulting in less resistance to expansion. On the other hand, the van der Waals equation accounts for intermolecular forces, leading to a higher effective pressure and increased resistance to expansion. Therefore, the work done by an ideal gas is greater than that done by a van der Waals gas during expansion.

Compression Work:
During compression, both gases require work to be done on them to reduce their volume. In this case, the attractive forces between molecules in a van der Waals gas result in a smaller decrease in volume compared to an ideal gas. Therefore, the work done on a van der Waals gas during compression is less than that done on an ideal gas.

Conclusion:
In conclusion, the work done by an ideal gas is more than that done by a van der Waals gas under isothermal reversible conditions. This is primarily due to the absence of intermolecular forces in ideal gases, resulting in less resistance to expansion and more work done during expansion. On the other hand, van der Waals gases experience attractive forces between molecules, leading to increased resistance to expansion and less work done.