Bond Energy Practice Problems

Phosphorus trichloride is formed when diphosphorus reacts with chlorine gas. The reaction equation is P₂ + 3 Cl₂ → 2 PCl₃. Calculate the ΔH for the reaction (in kcal and in kJ) using the bond dissociation energies in the table below.

Propyne (H–C≡C–CH₃) is being explored as rocket fuel for space crafts. Determine the ΔH for the combustion of propyne (in kJ/mol) using the bond dissociation energies in the table below.

The acetobacter bacteria can convert ethanol (C₂H₅OH) into acetic acid (CH₃COOH) via an aerobic process. The overall reaction is:

C₂H₅OH(l) + O₂(g) → CH₃COOH(l) + H₂O(l)

Calculate the ΔH for the reaction and use the bond dissociation energy in the table below even if the species are not in gaseous form. Report your answer in kcal/mol and kJ/mol. [C₂H₅OH: has five C–H bonds, one C–C bond, one C–O bond, and one O–H bond; CH₃COOH: has three C–H bonds, one C–C bond, one C=O bond, one C–O bond, and one O–H bond)