In: Chemistry
Assume that you measured ?Hrxn= -1290 kJ for the reaction:
2 HCN(g) + 5/2 O2(g) à2 CO2(g) + N2(g) + H2O(l)
Use your measured ?Hrxnwith literature values of ?Hf(CO2(g)) = -394 kJ/mol
and ?Hf(H2O(l)) = -286 kJ/mol to calculate the experimental ?Hffor HCN.
Given:
?Ho rxn = -1290.0 KJ/mol
Hof(O2(g)) = 0.0 KJ/mol
Hof(CO2(g)) = -394.0 KJ/mol
Hof(H2O(l)) = -286.0 KJ/mol
Balanced chemical equation is:
2 HCN(g) + 5 O2(g) ---> 2 CO2(g) + N2 (g) + H2O(l)
?Ho rxn = 2*Hof(CO2(g)) + 1*Hof(N2(g)) + 1*Hof(H2O(l)) - 2*Hof( HCN(g)) - 5*Hof(O2(g))
-1290.0 = 2*(-394.0) + 1*(0) + 1*(-286.0) - 2*Hof(HCN(g)) - 5*(0.0)
Hof(HCN(g)) = 108 KJ/mol
Answer: 108 KJ/mol