16.1. Solubility http://www.ck12.org
- Solutions can be unsaturated, saturated, or supersaturated, depending on the relationship between the solubility
of a substance and the amount that is actually dissolved. - The solubility of gases, liquids, and solids are affected by changes in temperature.
- Solutes and solvents that have similar polarities (i.e., both are polar, or both are nonpolar) tend to mix well,
creating homogeneous solutions. Solutes and solvents with very different polarities (i.e., one is polar, and the
other is nonpolar) often do not mix well, resulting in the formation of heterogeneous mixtures. - The solubilities of gases are often described as concentrations (i.e., mM or M) rather than the mass that can
be dissolved by a given mass of solvent. - The solubility of a gaseous solute is inversely related to the temperature of the solvent and directly proportional
to the partial pressure of the gas in the surrounding atmosphere. - Henry’s law describes the mathematical relationship between the concentration of a gaseous solute and its
partial pressure in the gas above the solution.
Lesson Review Questions
- Draw the mixture that would be formed when oil and water are combined.
- Give an example of molecular solid that dissolves in water due to polar-polar interactions.
- Ammonia (NH 3 ) dissolves well in water. Explain how this interaction might occur and the type(s) of inter-
molecular forces that would be involved. - Using the solubility-temperature curve inFigure16.1, describe conditions under which a solution of potas-
sium chloride would be unsaturated, saturated, and supersaturated at 20°C. - A solution is formed by dissolving 10. grams of potassium chlorate in 100. g of water at 30°C. If the solution
were heated to 40°C, how many more grams of solute could be dissolved? - A solution that is saturated with both methane and oxygen gas at 1 atm and 20°C is then heated to 40°C. What
will happen to the dissolved gases as the temperature increases? Referring back toFigure16.7, how much of
each gas would leave the solution? How much would remain? - Which of the gases inTable16.2 would have the highest solubility in water at 298 K? Which would have the
lowest solubility? - Urea (CH 4 N 2 O) is a molecular solid that has a relatively high solubility in water (seeFigure16.9). How
would you account for this fact?
FIGURE 16.9
The molecular structure for urea.- Which of the following substances would dissolve better in water: iodine crystals (I 2 ) or liquid methanol