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

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

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