- Physical Chemistry I
Spring 2012, Unique 52135
Lecture Summary, 25 January 2012
Gases Continued: 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
First Law of Thermodynamics: heat + work = Internal Energy
Work (w). Thermodynamic work is defined by changes in volume of the thermodynamic system. By convention, if w < 0, then the system has done work on the surroundings. If w > 0, then work has been done on the system.
Heat (q). Heat is the flow of energy into or out of a system that results in a change in temperature of that system. Heat and temperature are related through heat capacity, C, which is a property of a material.
Heat and work are path functions, meaning the magnitude of w and q depend on the path taken between initial and final states. We will spend much of the next couple days investigating the effects of various thermodynamic paths on heat and work.