Question

9. CH3Br reacts with OH with a room temperature rate constant of 2.9 x 10-14 cm3 molecule-1 s-1. (a) What is the lifetime of methyl bromide with respect to reaction with OH at a global mean concen tration of 5 x 105 molecules cm-3? (b) Colman et al. (1998) report an atmospheric lifetime of 0.8 0.1 years for methyl bromide. Since it is also taken up by soils and oceans, what must the lifetime with respect to uptake by soils and oceans be? Assume that the total lifetime r can be expressed as (see Seinfeld and Pandis page 21). (c) If the global mean OH concentration is really 1 x 106 molecules cm-3, what must the lifetime be with respect to uptake by soils and oceans?

Answer 1

Organic compounds are often identified using spectroscopy. The process of testing compounds using spectroscopy is fairly simple (the compounds are placed into the machine and the read-out is printed). The difficult part comes in learning how to read the print-out and determining what it is telling you.

In infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, we identify the compound based on specific groups. Certain ranges of frequencies for each type of spectroscopy indicate different groups