Final answer:
An isothermal process is one in which the temperature of a system remains constant throughout the process. During an isothermal expansion of an ideal gas in a sealed piston, the gas cools down and heat enters from the heat bath to maintain the temperature. The work done by the gas is positive and there is no change in the internal energy of the gas.
Step-by-step explanation:
An isothermal process is one in which the temperature of a system remains constant throughout the process. In the case of an ideal gas in a sealed piston, the gas expands isothermally when the weights on the piston are removed. During this expansion, the gas cools down and heat enters from the heat bath to maintain the temperature of the gas.
The work done by the gas during expansion can be calculated using the formula W = -PΔV, where W is the work done, P is the pressure, and ΔV is the volume change. Since the pressure decreases during the expansion, the work done by the gas is positive.
In an isothermal expansion, the change in the internal energy of the gas is zero. This is because the internal energy of an ideal gas is only dependent on its temperature, and since the temperature remains constant, there is no change in internal energy.
The relationship between pressure and volume during an isothermal expansion of an ideal gas is given by the equation PV = constant. This means that as the volume increases, the pressure decreases, and vice versa.