Chapter 2, Lesson 2: Factors Affecting Solubility
In this lesson you must be familiar with the following terminologies and personages ….
(please refer to your textbook pp. 63 – 95)
Factors Affecting Solubility
Solubility – the amount of a substance that dissolves in a given amount of solvent at a given
temperature to produce a saturated solution.
Saturated solution – a solution where no more solute appears to dissolve in a given
amount of solvent.
Unsaturated solution – a solution that contains less solute than a saturated solution.
Supersaturated solution – a solution that contains a greater amount of solute than
a saturated solution.
Seeding – the process of inducing crystallization to occur by adding a crystal to a
supersaturated solution.
Nature of the solute and solvent – substances with similar intermolecular forces of attraction
dissolve in each other and is usually expressed as “like dissolves like”.
Temperature – the solubility of most molecular and ionic solids increases with the increase in
temperature (endothermic).
Pressure – pressure has almost no effect in the solubility of solids and liquids, but has a srong
effect on the solubility of gases.
William Henry found out Henry’s Law. The solubility of a gas in a liquid at a given temperature is directly
proportional to the partial pressure of the gas over the solution.
Colligative properties – properties that depend on the amount of dissolved solute (concentration) and
not on the kind or chemical nature of the solute.
Electrolyte solutions / nonelectrolyte solutions
Vapor pressure reduction. Adding a nonvolatile solute to a pure solvent lowers the vapor pressure of the
solution at any given temperature. It follows that a solution must be heated to a higher
temperature
than that of a pure solvent in order to boil.
Francois Marie Raoult developed Raoult’s Law. The vapor pressure of a solution, PA, is equal to the mole
fraction of the solvent, XA, times the vapor pressure of the pure solvent, PAO.
Boiling point elevation
Freezing point depression
Osmotic pressure
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