The overall reaction is: CaCO3(s) CaO(s) + CO2(g) The decomposition reaction will only occur if the activity of the gas in contact with the solid has a value lower than the equilibrium value. The pressure of the gas at which the decomposition of the solid occurs is called the decomposition pressure. (a) Calculate the decomposition pressure of limestone at 1000 K. (b) Calculate the temperature that corresponds to a decomposition pressure of 1 bar. The following data are available: The standard free energy change of the reaction at 298.15 K is 134.3 kJ/mol. The standard enthalpy change of reaction at 298.15 K is 182.1 kJ/mol. The heat capacities of the two solids are: (Cp)cacoz 82.26 + 4.97x10-27 1.286x106 T2 J mol.K 4.51x105 (Cp)co = 41.8 + 2.02 x10-27 J mol.K T2