After isothermal compression, the energy of air will change, resulting in a decrease in internal energy.
During isothermal compression, the temperature of the air remains constant. Since temperature is a marker of the average kinetic energy of molecules, a constant temperature means that the average kinetic energy of gas molecules in motion remains unchanged. During isothermal compression, as the gas is compressed, the distance between molecules decreases. This leads to a decrease in the potential energy of intermolecular interactions, as the attractive and repulsive forces between molecules decrease with decreasing distance, but in this case, the main manifestation is a decrease in repulsive force, resulting in a decrease in potential energy. Due to the constant temperature, the average kinetic energy of gas molecules remains unchanged, so the kinetic energy portion has not changed. The reduction of molecular spacing leads to a decrease in the potential energy of intermolecular interactions, which is the main reason for the energy reduction during isothermal compression.
In the process of air compression, electricity is usually consumed to increase the air pressure. At the same time, the temperature of the gas will also increase. But in order to achieve isothermal compression, measures need to be taken to reduce the heat generated during the compression process and maintain the temperature constant. These cooling measures actually take away some energy, further reducing the internal energy of the compressed air.
