Question

CaO + CO2 gives CaCO3
why is this not an example of standard  molar enthalpy of formation?

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Answer 1

Explanation:

Given:

CaCO3(s)→CaO(s)+CO2(g),ΔH=42KJ

ΔH=ΔHf(CO2)+ΔHf(CaO)−ΔHf(CaCO3)

42=−94+(−152)−ΔHf(CaCO3)

42=−246−ΔHf(CaCO3)

=ΔHf(CaCO3)

−288KJ