CHEM 1211 Module Seven Quiz Name: _____________________

Part G: Hess Law of Constant Heat Summation 4 points

Using the following equations (if necessary)

2CH₄ (g) + 3 O₂ (g) à 2 CO (g) + 4 H₂O (l) ∆H˚ = -1215 kJ

2C (s) + O₂ (g) à 2 CO (g) ∆H˚ = -221 kJ

C (s) + O₂ (g) à CO₂ (g) ∆H˚ = -394 kJ

to calculate the enthalpy change for the reaction

CH₄ (g) + 2 O₂ (g) à CO₂ (g) + 2 H₂O (l) ∆H˚ = ?

Part H: Standard Enthalpies of Formation 4 points

When ammonia is oxidized to nitrogen dioxide and water, the quantity of heat released equals 349 kJ per mole of ammonia:

2NH₃ (g) + 7/2 O₂ (g) à 2 NO₂ (g) + 3 H₂O (l) ∆H˚ = -698 kJ

Calculate the standard molar enthalpy of formation of ammonia if

∆H˚_f (H₂O(l) ) = -286 kJ/mol ∆H˚_f (NO₂(g) ) = + 33 kJ/mol

Answer: Part G: -891 kJ Part H: -47 kJ/mol