# Van der waals equation and molar specific heat

1. Apr 22, 2014

### koustav

the van der waals equation of state is given by (p+an^2/v^2)(v-nb)=nRT.how to show that for a gas obeying the above equation of state (∂Cv/∂V) (taking temperature constant)=0?

2. Apr 24, 2014

### Khashishi

Just write out what the heat capacity means.
$C_v = \left(\frac{\partial{Q}}{\partial{T}}\right)_v = \left(\frac{\partial{U}}{\partial{T}}\right)_v$
You know how to calculate the internal energy U? Write it using the equation of state.

3. Apr 25, 2014