General Chemistry Principles, Patterns, and Applications, 2011

van’t Hoff factor? Batteries rely on a high concentration of unpaired Li + ions. Why is using a more
concentrated solution not an ideal strategy in this case?
3. Hydrogen sulfide, which is extremely toxic to humans, can be detected at a concentration of 2.0 ppb. At this
level, headaches, dizziness, and nausea occur. At higher concentrations, however, the sense of smell is lost,
and the lack of warning can result in coma and death can result. What is the concentration of H 2 S in
milligrams per liter at the detection level? The lethal dose of hydrogen sulfide by inhalation for rats is
7.13 × 10 −4 g/L. What is this lethal dose in ppm? The density of air is 1.2929 g/L.
4. One class of antibiotics consists of cyclic polyethers that can bind alkali metal cations in aqueous solution.
Given the following antibiotics and cation selectivities, what conclusion can you draw regarding the relative
sizes of the cavities?
Antibiotic
Cation Selectivity
nigericin K + > Rb + > Na + > Cs + > Li +
lasalocid Ba 2+ >> Cs + > Rb + , K + > Na + , Ca 2+ , Mg 2+
5. Phenylpropanolamine hydrochloride is a common nasal decongestant. An aqueous solution of
phenylpropanolamine hydrochloride that is sold commercially as a children’s decongestant has a
concentration of 6.67 × 10 −3 M. If a common dose is 1.0 mL/12 lb of body weight, how many moles of the
decongestant should be given to a 26 lb child?
6. The “freeze-thaw” method is often used to remove dissolved oxygen from solvents in the laboratory. In this
technique, a liquid is placed in a flask that is then sealed to the atmosphere, the liquid is frozen, and the flask
is evacuated to remove any gas and solvent vapor in the flask. The connection to the vacuum pump is closed,
the liquid is warmed to room temperature and then refrozen, and the process is repeated. Why is this
technique effective for degassing a solvent?
7. Suppose that, on a planet in a galaxy far, far away, a species has evolved whose biological processes require
even more oxygen than we do. The partial pressure of oxygen on this planet, however, is much less than that
on Earth. The chemical composition of the “blood” of this species is also different. Do you expect their
“blood” to have a higher or lower value of the Henry’s law constant for oxygen at standard temperature and
pressure? Justify your answer.
8. A car owner who had never taken general chemistry decided that he needed to put some ethylene glycol
antifreeze in his car’s radiator. After reading the directions on the container, however, he decided that “more
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