The enthalpy change was determined for the

following reactions;
Ca (s) + CO2 (g) + ½ O2 (g ) → CaCO3 (s)
ΔH = -812.8 kJ/mo l

Ca (s) + ½ O2 (g) → CaO (s)
ΔH = -634.9 kJ/mo l

What is the enthalpy change for the following reaction?

CaCO3 (s) → CaO (s) + CO2 (g)

1 answer

Add equation 1 to the reverse of equation 2 to obtain the reaction you want. dH for the new reaction is dH for equation 1 + the negative dH (which will make is positive) for equation 2.