Calculate the value of Delta H for the reaction CaCO3 --> CO2 + CaO from the following enthalpy changes:
Ca + C + 3/2 O2 --> CaCO3 ΔH = -1206.9 kJ
Ca + ½ O2 --> CaO ΔH = -635.1 kJ
C + O2 -->CO2 ΔH= - 393.5 kJ