Problem 8
List the three types of van der Waals forces in decreasing order of strength.
Problem 9
A hydrogen bond is a special case of what type of intermolecular force?
Problem 10
Why do you think that most textbooks do not consider a hydrogen bond to be an example of a van der Waals force?
Problem 11
What are some macromolecules that have hydrogen bonds as a part of their structures?
Problem 12
How are hydrogen bonds involved in the transfer of genetic information?
Problem 13
Rationalize the fact that hydrogen bonding has not been observed between \(\mathrm{CH}_{4}\) molecules.
Problem 15
What are the requirements for molecules to form hydrogen bonds? (What atoms must be present and involved in such bonds?
Problem 18
Both RNA and DNA have negatively charged phosphate groups as part of their structure. Would you expect ions that bind to nucleic acids to be positively or negatively charged? Why?
Problem 21
Aspirin is an acid with a \(\mathrm{p} K_{\mathrm{a}}\) of \(3.5 ;\) its structure includes a carboxyl group. To be absorbed into the bloodstream, it must pass through the membrane lining the stomach and the small intestine. Electrically neutral molecules can pass through a membrane more easily than can charged molecules. Would you expect more aspirin to be absorbed in the stomach, where the pH of gastric juice is about \(1,\) or in the small intestine, where the pH is about \(6 ?\) Explain your answer.
Problem 23
Calculate the hydrogen ion concentration, \(\left[\mathrm{H}^{+}\right]\) for each of the following materials: (a) Blood plasma, pH 7.4 (b) Orange juice, pH 3.5 (c) Human urine, pH 6.2 (d) Household ammonia, pH 11.5 (e) Gastric juice, pH 1.8
