Use the Gibbs–Helmholtz equation to find an expression for d ln x_A in terms of dT. Integrate d ln x_A from x_A = 0 to the value of interest, and integrate the right–hand side from the transition temperature for the pure liquid A to the value in the solution. Show that, if the enthalpy of transition is constant, then eqns 5.33 and 5.36 are obtained.