Final answer:
The total heat flow for the entire cyclic process involving an ideal gas expanding at constant pressure, cooling at constant volume, and then contracting without changing temperature, is zero joules.
Step-by-step explanation:
The student's question pertains to the heat flow involved in a series of processes undergone by an ideal gas. This question is typically addressed in the context of thermodynamics, a branch of physics that deals with heat and temperature and their relation to energy and work. Since the gas's initial and final temperatures are the same and no temperature change occurs during the process, the total heat flow for the entire cyclic process is zero.
The first step is an isobaric expansion where heat is absorbed by the gas. This heat (Q) can be calculated using the formula Q = PΔV, with P being the pressure and ΔV the change in volume. Since the process is isobaric (constant pressure), the heat absorbed during the expansion can be found by converting the pressure to Pascals and the volume change to cubic meters and then using the ideal gas law to find the work done by the gas, which in an isobaric process equals the heat transfer. The units of pressure and volume must be consistent with the work units desired (joules).
The second step is an isochoric process (constant volume) where the gas is cooled to its original temperature. In this process, no work is done since the volume does not change, and by the first law of thermodynamics, Q = ΔU + W, where ΔU is the change in internal energy and W is the work done by the gas. Since Q = W for an isobaric process and W = 0 for the isochoric cooling process, the heat released during cooling must equal the heat absorbed during the expansion, so they cancel out, making the net heat transfer zero.
The third step involves the gas contracting back to its original volume without changing temperature. Here again, the process is isothermal, and the heat released would be numerically equal to the work done in compression, thus canceling out the heat absorbed during the expansion.