PX275 - A2a - inexact differentials

• consider the change in the internal energy of a system, ie: D - the first law of thermodynamics:
  
• note: d bar used for inexact differentials
• the total expression is an exact differential, but it is the sum of inexact partial differentials
• "thermodynamic potentials" can used, where the variables involved are fully specified:$$dU=TdS-pdV$$where, $T$ is temperature, $S$ is entropy, $p$ is pressure, and $V$ is volume

PX284 - C2 - temperature