| Vf |
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| Vi |
A constant temperature process is an isothermal process. An example is when a gas in a container that is immersed in a constant-temperature bath is allowed to expand slowly, or is compressed slowly.
At constant temperature there is no change in internal energy.
DU = 0
Apply the First Law:
Q = W
The P-V diagram for this process follows an isotherm, a line of constant temperature.
For an ideal gas at constant temperature, the pressure is inversely proportional to the volume. This makes it straight-forward to do an integration to find that:
| Q = W | = nRT ln | ( |
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