Q. Enthalpy change for the reaction, 4H(g) → 2H₂(g) is −869.6 kJ. The dissociation energy of H–H bond is
A) +217.4 kJ
B) –434.8 kJ
C) –869.6 kJ
D) +434.8 kJ
Explanation
[Solution from source] 4H(g) → 2H₂(g) forms two H–H bonds and releases 869.6 kJ. Breaking one mole of H–H bonds therefore needs 869.6/2 = +434.8 kJ. Dissociation energy is always positive, so the negative values are wrong. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.