Concise Physical Chemistry

c21 JWBS043-Rogers September 13, 2010 11:30 Printer Name: Yet to Come

358 PHOTOCHEMISTRY AND THE THEORY OF CHEMICAL REACTIONS

Problem 21.3

Find the BDE for the following reactions within the G3(MP2) model chemistry:

CH 2 =CH−CH 3 →CH 2 =CH•+CH• 3

and

CH 2 =CH−CH 2 −CH 3 →CH 2 =CH−CH• 2 +CH• 3

Discuss the implications of this difference for free radical formation in unsaturated

fatty acids as contrasted to saturated fatty acids in physiological systems (Section

21.2.1). You will need to use data from Exercise 21.1.

Problem 21.4

Three coffee cups are arranged vertically A, B, C from top cup A to bottom cup C.

Cups A and B have holes in the bottom but C does not. A drains into B, and B drains

into C.

A→B→C

The hole in A is slightly larger than the hole in B. One cup of coffee is poured into

A. What happens?

1. Sketch the liquid levels in A, B, and C as a function of time.


2. The hole in A is made a little larger. Sketch A, B, and C as a function of time.


3. The hole in A is made a little larger still. Sketch A, B, and C as a function of
   time.


4. If the process is continued, what happens to level B?

Problem 21.5

Nitric oxide, NO, is very destructive to ozone in the stratosphere. (Commercial

supersonic jet flight has been banned because of the potential increase in stratospheric

NO.) Propose a mechanism for this destructive reaction.

Problem 21.6

The helium–neon laser produces light at 1152.3 nm. What is the energy of one mole

(aneinstein) of radiation at this wavelength?