Calculate the residual enthalpy and entropy for propane at \(312 \mathrm{~K}\) and \(2 \mathrm{MPa}\) using the van der Waals equation of state, given that \(a=0.877 \mathrm{~Pa}\left(\mathrm{~m}^{3} / \mathrm{mol}\right)^{2}, b=0.84 \times 10^{-4} \mathrm{~m}^{3} / \mathrm{mol}\).