CH353
- Physical Chemistry I Spring 2013 Unique 52575 Lecture Summary, 18 January 2013 |

Intermolecular
Forces Continued:
The idea of attractive and repulsive forces is put together in the
van der Waals equation, a state function for a real gas:P(vdW) = (nRT/(V-nb)) - a(n/V)^2a and b are constants that depend on the identity
of the gas and which determine the relative importance of attractive
and repulsive interactions. Although there are many other real
gas state functions, we will stick with the van der Waals equation
for any non-ideal system.When comparing a real gas to an ideal gas, a very helpful tool is compressibility, Z = VmP/RT.
If Z = 1, the gas is behaving identically to an ideal
gas. If Z > 1, the gas is dominated by repulsive
forces, and if Z < 1, the gas is dominated by
attractive forces. |