Untitled - Kelly Walsh High School

184 CHEMISTRY FOR THE UTTERLY CONFUSED
Don’t Forget!
To calculate the boiling point of the solution we use the relationship:
Tb iKbm We already have the van’t Hoff factor, K b, and solution molality so we can simply
substitute:
Tb iKb molality (3) (0.52°C/m) (0.545620951 m)
0.85116868°C (unrounded)
Tb (100.00 0.85116868)°C 100.85°C
The most common error made in colligative property problems is to forget to separate
the ions of an electrolyte. The van’t Hoff factor, even when not needed, is
a useful reminder.
In this chapter, you learned about solutions. A solution is a homogeneous mixture
composed of a solvent and one or more solutes. Solutions may be unsaturated,
saturated, or supersaturated. Solution concentration units include percentage,
molarity, molality, and mole fraction. The solubility of solids in liquids
normally increases with increasing temperature, but the reverse is true of gases
dissolving in liquids. The solubility of gases in liquids increases with increasing
pressure.
Colligative properties are those properties of solutions that depend on the number
of solute particles present and not their identity. Colligative properties
include vapor pressure lowering, freezing point depression, boiling point elevation,
and osmotic pressure. Colloids are homogeneous mixtures, in which the
solute particles are intermediate in size between suspensions and true solutions.
We can distinguish colloids from true solutions by the Tyndall effect.
1. What phrase applies to a situation where a polar solvent dissolves a polar
solute?
2. A solution containing the maximum amount of solute per given amount of
solvent at a given temperature is said to be
a. concentrated b. dilute c. unsaturated
d. saturated e. supersaturated