1. SOLUTIONS, SUSPENSIONS, AND COLLOIDS

2. Solution – a homogeneous mixture of two or more substances
solute – substance being dissolved
solvent – dissolving medium
For a salt water solution:
The solute is
salt
The solvent is
water

3. SOLUBILITY
The amount of a substance which will dissolve in a given amount of a particular solvent under certain conditions (ie. temperature and pressure.
Which substance has the
highest solubility at 20oC? KI
How many grams of KCl
will dissolve in 200 g of
water at 60oC?
90 g

4. soluble – will dissolve insoluble – will not dissolve
For all solutions:
soluble – will dissolve
insoluble – will not dissolve
For liquid/liquid solutions only:
Miscible - will dissolve
Immiscible – will not dissolve

5. General Concentration Terms
Unsaturated Solution – when less solute is dissolved in a solvent than is possible under the existing conditions
Saturated Solution – when as much solute is dissolved as possible under the existing conditions
Supersaturated Solution – when more solute is dissolved in a solvent than should be possible under the existing conditions

6. What would happen if a single “seed crystal” were added to:
An unsaturated solution?
It would dissolve
A saturated solution?
It would sink to the bottom
(it would not dissolve)
A supersaturated solution?
Crystals of solute will start precipitating

7. Factors Affecting the Rate of Solubility:
Heating Stirring Increasing Surface Area

8. Factors Affecting the Degree of Solubility:
For Solids:
In general, the solubility of a solid in a liquid increases as the temperature of the solvent increases.

9. For Gases:
1. In general, the solubility of a gas in a liquid decreases as the temperature of the liquid solvent increases.
2. Henry’s Law:
The solubility of a gas
in a liquid is directly
proportional to the
pressure of the gas over
over the liquid.

10. SUSPENSIONS
A heterogeneous mixture whose particles (which are relatively large) will settle out upon standing

11. COLLOIDS:
A homogeneous / heterogeneous (depending on the source!) mixture whose particles, which are intermediate in size, will not settle out upon standing

12. SOLUTIONS, SUSPENSIONS, AND COLLOIDS
CHARACTERISTICS OF
SOLUTIONS, SUSPENSIONS, AND COLLOIDS
PROPERTY
SOLUTIONS
COLLOIDS
SUSPENSIONS
Particle Size
Small
(0.1 – 1 nm)
Medium
(1-100 nm)
Large
(100 nm or larger)
Tyndall Effect No
Yes
Effect of Gravity
Do not settle out
Settle out
Filtration
Cannot be separated
Can be separated
Uniformity
Homogeneous
Borderline
Heterogeneous

13. The Tyndall Effect
The visible path produced by a beam of light passing through a colloidal mixture; caused by the scattering of light by the dispersed particles

14. EXAMPLES OF SOLUTIONS AND COLLOIDS
TYPE
SOLUTION
COLLOID
Solid/Solid
Alloys (brass, etc.)
Colored gems
Solid/Liquid
Ocean water
Jell-o, jelly, blood
(gels and sols)
Solid/Gas
Sulfur vapor in air
Smoke
Liquid/Solid
Mercury in copper
Pearls, Opals
Liquid/Liquid
Alcohol in water
Mayonnaise (emulsions)
Liquid/Gas
Fog
Hair spray (aerosols)
Gas/Solid
Hydrogen adhered to platinum
Ivory soap, marshmallows
Gas/Liquid
Dr. Pepper, Sprite
Whipped cream (foams)
Gas/gas
Air
NONE

15. colloidal mixtures of a solid dispersed in a liquid Emulsions
Gels and Sols
colloidal mixtures of a solid dispersed in a liquid
Emulsions
colloidal mixture of a liquid dispersed in a liquid
Aerosols
colloidal mixture of a liquid dispersed in a gas
Foam
colloidal mixture of a gas dispersed in a liquid