Work done by gas refers to the process of a gas expanding and performing work on its surroundings. This can occur when a gas is compressed or expands against a piston, for example.
Pexternal*dV, also known as the external pressure times the change in volume, is a mathematical representation of the work done by gas. It takes into account the force exerted by the gas and the change in volume of the gas.
Work done by gas can be calculated by multiplying the external pressure (Pexternal) by the change in volume (dV). This equation can be written as W=Pexternal*dV.
Some real-life examples of work done by gas include the expansion of a gas in a balloon, the compression of air in a car engine, and the expansion of steam in a steam engine. In each of these cases, the gas is performing work on its surroundings.
The concept of work done by gas is closely related to the first law of thermodynamics, which states that energy cannot be created or destroyed, only transferred or converted. In the case of work done by gas, the energy of the gas is converted into work as it expands or compresses. The second law of thermodynamics also plays a role, as it states that in any energy transfer or conversion, some energy is lost as heat. In the case of work done by gas, some of the energy of the gas is lost as heat to the surroundings.