Problem 2
How does temperature affect the solubility of \(\mathrm{O}_{2}\) in water? Explain what is meant by thermal pollution.
Problem 3
Define \(B O D\) and \(C O D\), and explain why their values for the same water sample can differ slightly. Explain why natural waters can have a high BOD.
Problem 5
Write the half-reaction, used in the COD titration, which converts dichromate ion to \(\mathrm{Cr}^{3+}\) ion, and balance it.
Problem 9
Explain the phenomenon of acid mine drainage, writing balanced chemical equations as appropriate. How does \(\mathrm{Fe}^{3+}\) also act as an oxidizing agent. here?
Problem 11
What are the acid and the base that dominate the chemistry of most natural water systems and whose interaction produces bicarbonate ion?
Problem 12
What is the source of most of the carbonate ion in natural waters? What name is given to waters that are exposed to this source?"
Problem 13
Write the approximate net reaction between carbonate ion and water in a system that is not also exposed to atmospheric carbon dioxide. Is the resulting water acidic, alkaline, or neutral?
Problem 15
If two equilibrium reactions are added together, what is the relationship between the equilibrium constants for the individual reactions and that for the overall reaction?
Problem 16
What is the natural source of fluoride ion in water? How and why is the fluoride level in drink. ing water artificially increased to about \(1 \mathrm{ppm}\) in many municipalities?
Problem 19
Which are the most abundant ions in clean, fresh water?
