1. Solution
Chemistry
Unit 10
Chapter 16

2. Vocabulary
Solution:
a homogenous mixture (substances are uniformly distributed and cannot be distinguished from one another)
Solvent:
the component of the solution present in the greatest quantity (usually H2O)
Solute:
the component present in quantity less than the solvent
Solubility:
ability of one substance to dissolve in another substance (H2O)
e.g.: solubility of NaCl is 35 g/L

3. Types of Solutions TYPE EXAMPLE liquid / liquid water / alcohol
liquid / solid
NaCl / water
liquid / gas
CO2 / water
gas / gas
N2 / O2 / CO (air)

4. Solubility & Polarity
Water is a good solvent because it is a polar substance
H O H
it is polar because electrons are held more closely by the oxygen (it is more electronegative than hydrogen) H O
( + ) ( + )
( - )
H O H
( + ) ( + )
( - )
and because the H2O is actually “V” shaped, one side of the molecule is slightly negative and the other side is slightly positive: it is polar

5. The most polar substances are ionic compounds e.g.: NaCl
- the sodium is (+)
- the chlorine is (-)
Polar substances dissolve in other polar substances.
Ionic example:
NaCl dissolving H O H O
( + ) ( + )
( - )
Cl-
Na+ + H O H O H O
Na+
Cl- H O H O H O
Ionic compounds dissociate into “hydrated” ions

6. Polar covalent example: CH3OH dissolving
( + ) ( + )
( - )
( - )
( + ) + H C O H O
“polar interactions” or “hydrogen bonding”

7. Non-polar covalent example:
CH4 does not dissolve in water. H C
- this molecule is non-polar, therefore, water will not interact with it.
This is why fats and oils don’t mix with water.
Fats and oils are non-polar.