To be clear, I have got two doubts,
- One, about the non-uniqueness of an isothermal process &
- Two, about the uniqueness of an adiabatic process.
The first doubt
The Wikipedia page of isothermal process states that:
For an adiabatic process, in which no heat flows into or out of the gas because its container is well insulated, Q = 0. If there is also no work done, i.e. a free expansion, there is no change in internal energy. For an ideal gas, this means that the process is also isothermal. Thus, specifying that a process is isothermal is not sufficient to specify a unique process.
Now I am confused about the meaning of the last line.
Thus, specifying that a process is isothermal is not sufficient to specify a unique process.
I am not able to understand the significance of that last statement. Does it mean that any two states, say A & B, can be connected by more than one isothermal processes?
The second doubt
Similarly, I had read in my textbook that an adiabatic process is unique in nature. That is, between any two states only one adiabatic process can exist. To say the same thing in other words, if two thermodynamic states are connected by a reversible adiabatic process, then the same two states cant be connected by an irreversible adiabatic process
Kindly help me understand these statements with the help of some PV/VT/PT diagrams.
Any help would be deeply appreciated.