Using the table of average bond energies below, the ΔH for the reaction is __________ kJ. H-C≡C-H (g) + H-I (g) → H₂C-CHI (g)
Bond: C≡C C=C H-I C-I C-H
D (kJ/mol) : 839 614 299 240 413

Question

Quizplus · Accepted Answer

The ΔH of the reaction can be calculated by subtracting the bond energies of the bonds broken from the bond energies of the bonds formed.
Bonds broken: 
- 1 C≡C bond (839 kJ/mol)
- 1 H-I bond (240 kJ/mol)

Bonds formed: 
- 1 C-I bond (240 kJ/mol)
- 1 C-H bond (413 kJ/mol)
- 1 S-H bond (372 kJ/mol)

ΔH = (240 + 839) - (240 + 413 + 372) = -129 kJ/mol

Therefore, the answer is choice D (-129).

Using the Table of Average Bond Energies Below, the ΔH