Download For 9/16/09

For 11/4/09 (do not hand in)
From the book:
Chapter 14: 1, 2, 3, 6, 9, 17, 18, 20, 22
Appendix E of the text has answers to even numbered questions
1. Hormones are chemical communicating substances that operate within an individual.
a. testes, ovaries, thyroid, immune system
b. testosterone
c. estrogen, progesterone
3. The chemical structures of estrogen mimics are unlike those of natural estrogens.
a. Some combinations of hormone-disrupting chemicals act synergistically,
that is, the effect of exposure to certain combinations of these chemicals far
exceeds the sum of the effects of exposure to each chemical singly.
b. Estrogen mimics have been shown to block the male hormone system,
affecting mating behavior, sperm counts, the structure of the prostate and
undescended testicles
c. infertility, premature births, neurological disorders, cancer
9. Its major source is the burning of chlorine-containing medical and municipal
wastes, the effluent from paper mills which used chlorine to bleach paper and
as a byproduct of the manufacture of trichlorophenol, a chemical that is used in
the manufacture of a variety of herbicides, including 2,4-D (Silvex).
a. yes
b. no (becomes associated with solids and sediments)
c. no (very slowly)
17. a. The Kow, is determined by measuring the concentration of a particular
compound in the water and the octanol phases after a period of mixing.
b. unitless
c. Octanol, a long-chain alcohol, mimics fat (lipids) and the Kow is an indication
of the tendency of a organic contaminate to bioaccumulate.
Other Problems:
Approximately how many trophic levels are required in the food chain to magnify
concentrations of a persistent organic by an approximate factor of 100?
Two trophic levels.
Draw the structure of 2 different PCB compounds that could give rise to the furan shown
when incinerated.
Compounds A, B, and C have log Kow values of 2.2, 6.8, and 9.5 respectively. Which of
these compounds is most likely to be ingested through eating food? Explain your
reasoning.
Compound B. The Kow for compound A is low enough that it will be ingested mostly
through drinking water, and the Kow for compound C is high enough that it is unlikely
that this compound will be effectively absorbed into the fatty tissues of living organisms.
In the case of PCBs, why is it feasible to clean up a contaminated area many years after
the contamination has occurred? In other cases, why is it not feasible?
Since most PCB were contained within large electronic equipment, the area of
contamination is usually limited. The fact that PCBs do not disperse quickly in the
environment also helps keep spills relatively contained.
Why would you expect compounds with a larger Kow value to take longer to decompose
in the environment?
The larger the Kow value, the less a compound will be found in the aqueous phase where
is may contact chemicals (such as acids) that might break it down. Compounds with
large Kows are also less likely to be volatile and will not be decomposed by atmospheric
oxidants.