# What are the things must be remember while studying adiabatic processes?

Aug 18, 2017

Well, it's always important to remember the definition of an adiabatic process:

$q = 0$,

So, there is no heat flow in or out (the system is thermally insulated from the surroundings).

From the first law of thermodynamics:

$\Delta E = q + w = q - \int P \mathrm{dV}$

where $w$ is the work from the perspective of the system and $\Delta E$ is the change in internal energy.

For an adiabatic process, we then have $\underline{\Delta E = w}$, so if the system expands, the internal energy of the system decreases as a direct result of the expansion work only.

From the second law of thermodynamics:

$\Delta S \ge \frac{q}{T}$

where $>$ corresponds to irreversible processes and $=$ corresponds to reversible processes.

If there is absolutely no heat flow in or out, the system entropy should be constant, as long as the process is reversible. You can read more about reversible processes here.