##Van## ##der## ##Waals## ##equation##:
Van der Waals equation is used with amendment of ideal gas
Equation:
Amendment for volume:
Volume of an ideal gas ##V##.When the *real * gas is kept in that ##V## volume volume occupied by real gas is ##x##. Then the volume of an ideal gas is ##(V-x)##
Amendment for pressure:
Pressure of an ideal gas is ##P##. Measured pressure of real gas is ##p##. Pressure reduced due to intermolecular attraction of real gas is ##y##.
If we add measured pressure of real gas and pressure reduced due to intermolecular attraction of real gas is equal to the the pressure of ideal gas.
##P=p+y##
Therefore Van der Waals equation is:
##a## and ##V## are constants for real gases. This equation can be used in any temperature and pressure.
This equation is equal to ideal gas at high tempareture and low pressure. Because:
##p##+##a##(##n^2##/##v^2##) is almost equal to ##p## and ##V-nb## is almost equal to ##V##
becuase
So for real gases
##a## & ##V## are constant. Therefore they deviate from ideal gas behavior.
Deviation is as follows: