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Formula Van der Waals Equation Pressure    Temperature    Covolume    Cohesion parameter    Gas constant

Formula
Formula: Van der Waals Equation

Pressure

Unit
Pressure of the (real) gas. With the real gas - in contrast to the ideal gas - the gas pressure may be very high.

Temperature

Unit
Temperature of the (real) gas. With the real gas - in contrast to the ideal gas - the temperature of the gas may be low.

Volume

Unit
Volume of the (real) gas. Molar volume: \( V_{\text m} ~=~ \frac{V}{n} \).

Amount of substance

Unit
Amount of substance indirectly indicates the number of particles of the gas.

Covolume

Unit
Covolume is the material-dependent intrinsic volume of the particles of the real gas. It reduces the volume \( V \) available for the motion of the particles to \( (V ~-~ n\,V_{\text b}) \). For the ideal gas, the following holds: \( V_{\text b} ~=~ 0 \). The unit of covolume is \( \mathrm{m}^3 / \mathrm{mol} \).

Cohesion parameter

Unit
Cohesion parameter is a material-dependent quantity that indicates the force between the particles of the gas. In the case of an ideal gas, the following holds true: \( a ~=~ 0 \). The term \( \frac{n^2 \, a}{V^2} \) is called internal pressure. The unit of the cohesion parameter is \( \mathrm{Pa}\,\mathrm{m}^6 / \mathrm{mol}^2 \).

Gas constant

Unit
Gas constant is a physical constant with the value: \( R = 8.314 \, \frac{\text J}{\text{mol} \, \text{K}} \).