Consider these intermediate chemical equations. Ca times s plus CO sub 2 times g plus 1 half cap o sub 2 g rightarrow Ca CO sub 3 s triangle cap h sub 1 is equal to negative 812 point 8 kJ 2 Ca s plus cap o sub 2 times g rightarrow 2 Ca cap o s triangle cap h sub 2 is equal to negative 1 comma 269 point 8 kJ The final overall chemical equation is CaO times s plus CO sub 2 times g rightarrow Ca CO sub 3 s . When the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation