Question

Calculate the DH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. DH°f means delta or change of heat of formation 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)

Answer 1

Answer: +178.3 kJ

Explanation:

The chemical equation  follows:

$CaCO_3(s)\rightarrow CaO(s)+CO_2(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(CaO(s))})+(1\times \Delta H^0f_{CO_2}]-[(1\times \Delta H^o_f_{(CaCO_3(s))})]$

We are given:

$\Delta H^o_f_{(CaO(s))}=-635.1kJ/mol\\\Delta H^o_f_{(CaCO_3(s))}=-1206.9kJ/mol\\\Delta H^o_f_{(CO_2(g))}=-393.5kJ/mol\\\Delta H^o_{rxn}=?$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times (-635.1))+(1\times (-393.5))]-[(1\times (-1206.9))]$

The DH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide is +178.3 kJ