Two litre of N2 at 0^∘ C and 5 atm pressure are expanded...

Two litre of $\mathrm{N}_{2}$ at $0^{\circ} \mathrm{C}$ and 5 atm pressure are expanded isothermally against a constant external pressure of 1 atm until the pressure of gas reaches 1 atm. Assuming gas to be ideal, calculate work of expansion.

Key Concepts

Isothermal Process

An isothermal process is one during which the temperature of the system remains constant. For an ideal gas, this means that the internal energy does not change, and any work done by the gas is exactly balanced by heat transfer, ensuring the temperature remains fixed throughout the process.

Constant External Pressure Expansion

When a gas expands against a constant external pressure, the work done by the gas is calculated simply as the product of the external pressure and the change in volume. This approach is typical for irreversible processes where the external pressure remains fixed, rather than matching the instantaneous pressure of the gas at all times.

Work in Thermodynamics

Work in thermodynamics represents the energy transferred when a force moves the boundary of a system. In the context of gas expansion, it is quantified as the product of pressure and the change in volume. The sign convention usually assigns negative work when the system does work on the surroundings during an expansion.

Ideal Gas Law

The ideal gas law, expressed as PV = nRT, links the pressure, volume, temperature, and the number of moles of an ideal gas. This equation is essential in thermodynamics for describing the state of a gas and for calculating how changes in one state variable affect the others during processes such as expansion or compression.

Irreversible Process

An irreversible process is one that cannot be simply reversed to restore both the system and its surroundings to their original states. In the context of gas expansion against a constant external pressure, irreversibility arises because the process does not proceed through a continuous series of equilibrium states, making the work done different from that calculated along a reversible path.

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