Concise Physical Chemistry

ans JWBS043-Rogers September 15, 2010 1:22 Printer Name: Yet to Come

368 ANSWERS TO SELECTED ODD-NUMBERED PROBLEMS

CHAPTER 19

19.1a−168 kJ mol−^1 ;19.1b−7kJmol−^1 ;19.3 105. 1 ◦. The experimental value

is 104. 5 ◦;19.7− 31 .7 kcal mol−^1 =− 132 .7kJmol−^1. The experimental value is

− 32. 60 ± 0 .05 kcal mol−^1 = 136. 4 ± 0 .2kJmol−^1.

CHAPTER 20

20.3the degeneracy pattern is 1,2,1,2, unlike the 1,2,2,1 pattern in the more common

Huckel model;20.7aUHF=−2.8874388;20.7bUHF=−4.8708157;20.7cThe

molecule does not exist;20.7dThe molecule is lower in energy than its atoms by

30.3 kcal mol−^1 =127 kJ mol−^1. LiH exists and is used in organic chemistry as a

reducing agent.

CHAPTER 21

21.1search for PhCH 2 CH 2 Ph in the product mixture;21.3 100 .2 kcal mol−^1 and

74 .2 kcal mol−^1 ;21.70.17.