Use bond energy values to calculate the enthalpy change in kJ for the reaction represented in the equation below. Give the quantity and unit, and don’t forget the + or - sign.

Question

Use bond energy values to calculate the enthalpy change in kJ for the reaction represented in the equation below. Give the quantity and unit, and don’t forget the + or - sign. H2 +Cl2 ——> 2HCL

Answer 1

Formula for Bond Energy Calculations

Σ (Bonds Broken- Bonds Formed)

H₂ + Cl₂ ----------------> 2 HCl

(432 kj/mol) + 239 kj/mol 2 (427 kj/mol)

671 kj/mol - 854 kj/mol = -183 kj/mol

(Reaction is Exothermic)