This preview shows page 1. Sign up to view the full content.
Unformatted text preview: H Br
5 + H Br ≈ 1600 ΔH° = +34 kJ/mol 99.4% 0.6% reaction reaction 6 1 11/19/2010 Why is the ∆∆H* for bromination larger than that for chlorination? Hammond's postulate
The transition state for an exothermic step resembles the reactants. The transition state for an endothermic step resembles the products. Hammond's postulate
C H ∆ ∆H* = 4 kJ/mol
C H Br ∆ ∆H* = 18 kJ/mol C H−Br
C H Br Hammond's postulate
C H Cl
Cl C H−Cl C H
C H C
energy energy energy
C C H Br H−Br H C H energy C H Cl C H−Cl C H C H energy C H ∆ ∆ H° = 21 kJ/mol reaction ∆ ∆ H° = 21 kJ/mol reaction
7 reaction reaction reaction 8 W...
View Full Document
This note was uploaded on 12/05/2010 for the course CHE 321 taught by Professor Fowler/sampson during the Fall '08 term at SUNY Stony Brook.
- Fall '08