The state of a real gas if changed from pressure p1, temperature T1 to pressure p2 temperature T2. The change in enthalpy, h1 – h2, is given by
1. \(\mathop \smallint \limits_{{T_1}}^{{T_2}} {C_p}dT\)
2. \(\mathop \smallint \limits_{{T_1}}^{{T_2}} {C_p}dT + \mathop \smallint \limits_{{p_1}}^{{p_2}} {\left( {\frac{{\partial V}}{{\partial p}}} \right)_T}dp\)
3. \(\mathop \smallint \limits_{{T_1}}^{{T_2}} {C_p}dT + \mathop \smallint \limits_{{p_1}}^{{p_2}} \left[ {V - T{{\left( {\frac{{\partial V}}{{\partial T}}} \right)}_p}} \right]dp\)
4. \(\mathop \smallint \limits_{{T_1}}^{{T_2}} {C_p}dT + \mathop \smallint \limits_{{p_1}}^{{p_2}} \left[ {V - T{{\left( {\frac{{dV}}{{dP}}} \right)}_T}} \right]dp\)