Calculate the DH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. DH°f [CaCO3(s)] = –1206.9 kJ/mol; DH°f [CaO(s)] = –635.1 kJ/mol; DH°f [CO2(g)] = –393.5 kJ/mol CaCO3(s) --> CaO(s) + CO2(g)

ΔHrxn for this reaction is  178.3 kJ/mol

Explanation:

Step 1: Data given

ΔH°f [CaCO3(s)] = –1206.9 kJ/mol

ΔH°f [CaO(s)] = –635.1 kJ/mol

ΔH°f [CO2(g)] = –393.5 kJ/mol

Step 2: The balance equation

CaCO3(s) --> CaO(s) + CO2(g)

Step 3: Calculate ΔHrxn

ΔHrxn = The sum of ΔHf of the products - ΔHf of the reactants

ΔHrxn = ((-393.5 kJ/mol) + (-635.1 kj/mol)) - (-1206.9 kJ/mol)

ΔHrxn = 178.3 kJ/mol

ΔHrxn for this reaction is  178.3 kJ/mol

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