Question 7.C-L.3: a. Refer to Table 7.4 and decide which of the following salt...
a. Refer to Table 7.4 and decide which of the following salts you would use as a solute if you wanted to prepare a solution that contained as many barium ions (Ba^{2+}) as possible: BaSO_4, Ba(NO_3)_2 , or BaCO_3. Explain your answer.
b. A common sight on the evening TV news in the late 1960s and 1970s was sea birds soaked with crude oil being cleaned by concerned people. Which of the following do you think was used to clean the oil from the birds? Explain your answer. Light mineral oil, purified water, seawater, or gasoline.
| Table 7.4 General Solubilities of Ionic Compounds in Water | ||
| Compounds | Solubility | Exceptions |
| Group IA (Na^{+}, K^{-}, etc.) and NH_{4}^{+} | Soluble | |
| Nitrates (NO_{3}^{-} ) | Soluble | |
| Acetates (C_{2}H_{3}O_{2}^{-} ) | Soluble | |
| Chlorides (Cl^{-}) | Soluble | Chlorides of Ag^{+}, Pb^{2+}, Hg^{+} (Hg^{2+}_{2} ) |
| Sulfates (SO_{4}^{2-} ) | Soluble | Sulfates of Ba^{2+}, Sr^{2+}, Pb^{2+}, Hg^{+} (Hg^{2+}_{2} ) |
| Carbonates (CO_{3}^{2- } ) | Insoluble^{a} | Carbonates of group IA and NH_{4}^{+} |
| Phosphates (PO_{4}^{3-} ) | Insoluble^{a} | Phosphates of group IA and NH_{4}^{+} |
a. The solubility of nitrates and lack of solubility of sulfates and carbonates of barium makes barium nitrate, Ba(NO_3)_2, the salt to use. More of it would dissolve and would release more Ba^{2+} ions.
b. Like dissolves like, so oil will dissolve best in oily solvents such as light mineral oil or gasoline. Light mineral oil is the solvent used because it leaves a residue that is similar to the natural oily secretions found on the bird feathers. Gasoline would be hazardous to use (flammable) and leaves no such useful residue.