At 850°C, CaCO3 undergoes substantial decomposition to yield CaO and

At 850°C, CaCO3 undergoes substantial decomposition to yield CaO and CO2. Assuming that the (H°f values of the reactant and products are the same at 850°C as they are at 25°C, calculate the enthalpy change (in kJ) if 66.8 g of CO2 are produced in one reaction?