the reaction can either be reactant or product favored :)

For the reaction CaCO3(s)CaO(s)+CO2(g) G=129kJ and H=178kJ at 302K and 1atm. This reaction is favored under standard conditions at 302K. The entropy change for the reaction of 2.11 moles of CaCO3(s) at this temperature would be J/K