Problem 3
In a particular fresh water sample, the concentrations of cations and anions are (in \(\mu \mathrm{mol} \mathrm{L}^{-1}\) ): \(\begin{array}{lrlr}\mathrm{Na}^{+} & 33 & \mathrm{Cl} & 120 \\\ \mathrm{~K}^{+} & 4 & \mathrm{NO}_{3}^{-} & 13 \\ \mathrm{Mg}^{2+} & 31 & \mathrm{HCO}_{3}^{-} & 270 \\ \mathrm{Ca}^{2+} & 160 & \mathrm{CO}_{3}^{2} & 0.67 \\ & & \mathrm{SO}_{4}^{2-} & 11\end{array}\) Compare the concentration of total positive and negative charge in the solution. Assume that the difference is due to hydronium or hydroxyl ion, and calculate the \(\mathrm{pH}\).
Problem 4
The major ions and their concentration (mmol L -1) in sea water are: \(\begin{array}{lrlr}\mathrm{Na}^{+} & 470 & \mathrm{~K}^{+} & 10 \\\ \mathrm{Mg}^{2+} & 53 & \mathrm{Ca}^{2+} & 10 \\ \mathrm{Cl}^{-} & 547 & \mathrm{SO}_{4}^{2-} & 28 \\ \mathrm{Br}^{-} & 1 & \mathrm{HCO}_{3}^{-}+\mathrm{CO}_{3}^{2-} & x\end{array}\) Assume that charges of these species balance and calculate the total concentration of negative charge associated with the two carbonate species. With a pH of 8.2, calculate the concentrations of the two individual carbonate species.
Problem 7
The following are controlling factors for the 'availability' of different elements: \- oxygen availability for iron \- sulfide concentration for zinc \- solution pH for chromium and silicon \- carbonate concentration for calcium \- sorption factors for copper. Explain the chemical and environmental significance of these factors.
