One mole of solid Cr ₂ O ₃ at 2500 K is dissolved in a large volume of a liquid Raoultian solution of Al ₂ O ₃ and Cr ₂ O ₃ in which X _Cr2O3 = 0.2 and which is also at 2500 K. Calculate the changes in enthalpy and entropy caused by the addition. The normal melting temperature of Cr ₂ O ₃ is at 2538 K, and it can be assumed that the ΔS _m,Al2O3 = ΔS _m,Cr2O3.