Answer: Using Three Equations with Hess’s Law to Calculate

Chapter , Problem 2PE

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Problem 2PE

Using Three Equations with Hess’s Law to Calculate ΔH

Calculate ΔH for the reaction

2 C(s) + H2(g) → C2H2(g)

given the following chemical equations and their respective enthalpy changes:

C2H2(g) + 5/2 O2(g) → 2 CO2(g) + H2O(l) ΔH = -1299.6 kJ

C(s) + O2(g) → CO2(g) ΔH = -393.5 kJ

H2(g) + ½ O2(g) → H2O(l) ΔH = -285.8 kJ

Calculate ΔH for the reaction

NO(g) + O(g)→ NO2(g)

given the following information:

NO(g) + O3(g) → NO2(g) + O2(g) ΔH = -198.9 kJ

O3(g) → 3/2 O2(g) ΔH = -142.3 kJ

O2(g) → 2 O(g) ΔH = 495.0 kJ