Difference between Cp and Cv

[Catherine_Zhang_1H]

I'm having trouble understanding why there is only a difference in gases between Cp and Cv and how that would affect how to solve a problem (like would we have to distinguish which one should be used?) if someone could help out. Thanks

[AndyL3I]

Cp is the specific heat of a substance under constant pressure, whereas Cv is the specific heat of a substance under constant volume. The problem will usually specify whether the system is under constant pressure or constant volume and you would use Cp or Cv accordingly.