LearnChemE

#### Reversible and Irreversible Expansion/Compression Processes: Screencasts

Shows graphically the areas on a pressure-volume diagram that are proportional to work for reversible and irreversible expansions and compressions of a gas in a piston/cylinder.

We suggest you list the important points in this screencast as a way to increase retention.

Shows reversible and irreversible processes on an enthalpy-entropy diagram, and discusses the work for the two types of processes.
We suggest you list the important points in this screencast as a way to increase retention.
##### Important Equations:

For an ideal gas:

$$\Delta U = C_V \Delta T$$ $\Delta H = C_P \Delta T$

For reversible or irreversible processes:

$W = – \int P_{ext} dV$

where $$P_{ext}$$ is the external pressure

For reversible processes:

$W = – \int PdV,$

where $$P$$ is the gas pressure

For irreversible processes with a constant external pressure $$(P_{ext})$$:

$W = – P_{ext} \Delta V,$

where $$P_{ext}$$ is the final external pressure

For an ideal gas in a reversible, adiabatic process:

$\Delta S = 0$

Adiabatic reversible expansion or compression (open or closed system) for an ideal gas:

$\frac {T_2}{T_1} = \left( \frac {P_2}{P_1}\right)^{\frac{R}{C_P}}$