# 9. solutions

```Solution: a homogenous mixture made up of two or more
substances (aka: aqueous). A solution is made up of a solute
and a solvent.
Solute: a substance like salt or sugar that dissolves in a
solvent like water.
Solvent: usually a liquid, for example water. If the solvent is
water, then the solution is called an aqueous solution (aq).
Factors Affecting the Rate of Dissolving



Surface area
Stirring
Temperature
Factors Affecting Solubility
1. Temperature:

Solids and liquids: as temperature increases,
solubility increases

Gases: as temperature increases, solubility
decreases
2. Nature of Solute/Solvent:
“Likes dissolve in likes”
 Polar solutes will only dissolve in polar
solvents
 Non-polar solutes will only dissolve in
non-polar solvents
 Water is polar


(polar= ionic or polar covalent)
3. Pressure:
 Pressure only has an affect on gases.
 Has NO affect on solids or liquids.
 This is how soda maintains its “FIZZ”,
once the soda can is opened the CO2
in solution is released into the
atmosphere and soda goes “FLAT”.
Table G: Solubility Curve
HCl
NH3
SO2

There are three types of solutions:
◦ saturated
◦ unsaturated
◦ supersaturated
The slopes on Table G represent
SATURATED!!! Any amount above is
supersaturated, any amount below is
unsaturated.
 You can determine how much solute

settles out, precipitates, re-crystalizes
using this table as well.
Soluble or Insoluble? (Table F)
Soluble
Insoluble
Insoluble
Soluble
Molarity

The molarity of a solution is the number of moles of
solute in one liter of a solution.
Molarity (M) = moles of solute
liters of solution
Parts Per Million (ppm)

A unit of concentration that expresses the mass of a solute
dissolved in 1 million parts of a very diluted solution.
ppm = grams of solute x 1,000,000
grams of solution
Percent by Mass

Similar concept as percent composition (part/whole x 100).
Looking to calculate the percent mass of solute in the whole
solution.
% Mass = grams solute x 100
grams solution
Boiling Point Elevation:
 Rule: The presence of a solute (salt or sugar) raises the
boiling point of the solvent.
Freezing Point Depression:
 Rule: The presence of any solute (salt or sugar) lowers the
freezing point of the solvent.

This is how we are able to melt ice from
pavement; make ICE CREAM; speed up
cooking time when boiling water is required.
```