Heat Changes Associated with Chemical Reactions, Hess’ Law, and Reaction Profiles

Using your knowledge of Hess’s Law, determine the enthalpy change for each reaction shown below. Remember, to find the enthalpy change you must first find the enthalpy of the intermediate reactions. If a reaction does not match it must be reversed according the Hess’s Law.

This activity is available below or in printable version.

1. The enthalpy changes for the following reactions can be measured:

Reaction	Enthalpy
N2 (g) + O2 (g) → 2NO (g)	ΔH= -180.5 kJ
N2 (g) + 3 H2 (g) → 2NH3	ΔH= -91.8.0 kJ
2H2 (g) + O2 (g) → 2H2O (l)	ΔH= -483.6 kJ

Use these values and Hess’s Law to determine the enthalpy change for the reaction:

2. The enthalpy changes for the following reactions can be measured:

Reaction	Enthalpy
C2H4 (g) + 3 O2 (g) → 2CO2 (g) + 2 H2O (l)	ΔH= -1411.0 kJ
C2H6 (g) + 3 ½ O2 (g) → 2CO2 (g) + 3H2O (l)	ΔH= -1560.0 kJ
C2H4 (g) + H2 (g) →C2H6 (g)	ΔH= -137.0 kJ

Use these values and Hess’s Law to determine the enthalpy change for the reaction:

3. The enthalpy changes for the following reactions can be measured:

Reaction	Enthalpy
C2H5OH (l) + 2O2 (g) → 2 CO2 (g) + 2H2O (l)	ΔH= -875.0 kJ
C (s) + O2 (g) → CO2 (g)	ΔH= -394.51.0 kJ
H2 (g) + ½O2 (g) → H2O (l)	ΔH= -137.0 kJ

Use these values and Hess’s Law to determine the enthalpy change for the reaction:

Once you have completed this assignment, please submit your work to the dropbox.