Final answer:
In a reversible adiabatic process, it is false that internal pressure and external pressure are equal at every step. Adiabatic processes involve no heat transfer and result in temperature and pressure changes due to work done by or on the system.
Step-by-step explanation:
Is Internal Pressure Equal to External Pressure in a Reversible Adiabatic Process?
In a reversible adiabatic process, the statement that the internal pressure and external pressure are equal in every step is false. During an adiabatic process, there is no heat transfer (Q = 0), which implies that any work done by or on the system results in a change in the internal energy of the system. During adiabatic expansion, for example, the work is done at the expense of the internal energy, resulting in a decrease in temperature. This decrease in temperature leads to a decrease in internal pressure.
The misconception may arise from the principles of reversible processes, where the system can undergo infinitesimally small changes where the system is always in quasi-static equilibrium, which can give the impression that the internal and external pressures are equal. However, in an adiabatic process, while it's true that the process is reversible and can return to its initial state, the pressures will differ due to the absence of heat transfer, especially when comparing with an isothermal process where the temperature (and thus the internal energy and pressure for an ideal gas) remains constant.
To further clarify, during an adiabatic expansion, a gas does work, and the energy for this work comes from the internal energy of the gas, resulting in a cooler gas and lower internal pressure compared to an isothermal expansion where the temperature and therefore pressure remain constant.