#### 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.

##### 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:

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