Question

1/

a/

Calculate the change in enthalpy of the reaction below using Hess's law.
S (s) + O2 (g) 
→  SO2 (g)

(1) 2 SO2 (g) + O2 (g) 
→  2 SO3 (g)                    ΔH = - 196 kJ
(2) 2 S (s) + 3 O2 (g) 
→ 2 SO3 (g)                     ΔH = - 790 kJ

b/

Calculate the change in enthalpy of the reaction below using Hess's law.
N2O4 (g) 
→  2NO2

(1) 2NO2 (g) 
→  2NO (g) + O2 (g)                   ΔH = +109 kJ / mol
(2) 1/2 N2 (g) + 1/2 O2 (g) 
→ NO (g)                              ΔH = +90.0 kJ / mol
(3) N2 (g) + 2O2 (g) 
→  N2O4 (g)                           ΔH = +8.0 kJ / mol

c/

 Calculate the enthalpy change of the reaction below using Hess's law.
2CO2 (g) + 3H2O (l) 
→ C2H6O (l) + 3O2 (g)

(1) 2C2H4O (l) + 2H2O (l) → 2C2H6O (l) + O2 (g)                  ΔH = 1017.5kJ
(2) C2H4O (l) + 5 / 2O2 (g) → 2CO2 (g) + 2H2O (g)                ΔH = -2 917.5kJ

Answer 1