1. What are Mixtures and Solutions?
 A MIXTURE is a combination of two or more substances that are not chemically united and do not exist in fixed proportions to each other. Most natural substances are mixtures.In the graphic on the left there are four substances - water, alcohol, oil, and food color dye.

2.  MIXTURES
 PURE COMPOUNDS
 A mixture can be physically separated into pure compounds or elements.
 A pure compound has a constant composition with fixed ratios of elements.
 Just about everything that you can think of is probably a mixture. Even the purest of materials still contain other compounds as impurities.
Although it is almost physically impossible to isolate absolutely pure substances, a substance is said to be pure if no impurities can be detected using the best available analytical techniques.
 Mixtures may exhibit a changing set of physical properties.
For example, mixture of alcohol and water boils over a range of temperatures.
Physical properties such as boiling point or melting point of pure substances are invariant.
For example, pure water boils at 100 degrees C

3. HETEROGENEOUS MIXTURES
 HOMOGENEOUS MIXTURES
HETEROGENEOUS MIXTURES
 The prefixes"homo"- indicate sameness
Theprefixes: "hetero"- indicate difference.
A homogeneous mixture has the same uniform appearance and composition throughout. Many homogeneous mixtures are commonly referred to as solutions. Particle size distinguishes homogeneous solutions from other heterogeneous mixtures. Solutions have particles which are the size of atoms or molecules - too small to be seen.
A heterogeneous mixture consists of visibly different substances or phases. The three phases or states of matter are gas, liquid, and solid.
Graphic on the left of "Dancing Raisins" shows liquid, solid, and gas substances in a heterogeneous mixture.

4. Colloid and suspension
In contrast a suspension is a heterogeneous mixture of larger particles. These particles are visible and will settle out on standing. Examples of suspensions are: fine sand or silt in water or tomato juice.
A colloid is a homogeneous solution with intermediate particle size between a solution and a suspension. Colloid particles may be seen in a beam of light such as dust in air in a "shaft" of sunlight.
Milk, fog, and jello are examples of colloids.

5. Homogeneous and Heterogeneous
Corn oil is homogeneous, White vinegar is homogeneous. A sugar solution is homogeneous since only a colorless liquid is observed. Air with no clouds is homogeneous.
Beach sand is heterogeneous since you can see different colored particles. Vinegar and oil salad dressing is heterogeneous since two liquid layers are present, as well as solids. Air with clouds is heterogeneous, as the clouds contain tiny droplets of liquid water.

6. SOLUTIONS 
SOLUTIONS are homogeneous mixtures. A solution is a mixture of two or more substances in a single phase. At least two substances must be mixed in order to have a solution. The substance in the smallest amount and the one that dissolves or disperses is called the SOLUTE. The substance in the larger amount is called the SOLVENT. In most common instances water is the solvent. The gases, liquids, or solids dissolved in water are the solutes.In the graphic, the blue bottle is a homogeneous solution mixture of water, KOH, glucose, oxygen gas dissolved, and methylene blue - an indicator.  
Since solutions are mixtures, their compositions may vary over a very wide range. The concentrations may be expressed using a variety of measures. The non-specific terms concentrated and dilute are sometimes used. A concentrated solution has a relatively large (but non-specific) amount of solute dissolved in a solvent. A dilute solution has a smaller quantity of solute dissolved. 

8. TYPES OF SOLUTIONS Concentrations Solute Less than 50%
Solute Less than 50%
Solvent More than 50%
 Examples
 liquid
 alcohol - water
wine beer, vodka acetic acid / water - vinegar
 solid
liquid
 salt - water
saline (NaCl) solution sugar solution CaCO3 - hard water
 gas
 oxygen - water
 CO2 - carbonated water NH3 - ammonia solution
air = oxygen -nitrogen
 hydrogen - platinum
gas
 water in air
smog
solid
 mercury - another metal
 alloy

9. Density  
Example
In a mixture of oil, water, and sand the density of oil < the density water < the density sand

10. Particle Size
Example
In a mixture of clay, sand, and pebble the particle size of clay < the particle size of sand < the particle size of pebble. 

11. Particle Size
Example
In a mixture of sand and water the sand can be filtered out.

12. Filtration
This is good for separating an insoluble solid from a liquid (an insoluble substance does not dissolve in water). For example, sand can be separated from a mixture of sand and water using filtration.

13. Molecular polarity
Molecules that are polar attracts one another and other polar molecules. Those attractions are called intermolecular forces. Molecular polarity ranges from none to high. The higher the molecular polarity the stronger the intermolecular force is.

14. Molecular polarity
Example

15. Boiling and freezing points
Distillation is the process of separating substances from a mixture according to their respective boiling points.

16. Boiling and freezing points
Example
In a mixture of alcohol and water the alcohol will boil first since it has a lower boiling point than water. The alcohol vapor is then condensed and collected

17. Fractional distillation
This is good for separating two or more liquids from each other. For example, ethanol (alcohol) can be separated from a mixture of ethanol and water by fractional distillation. This method works because the two liquids have different boiling points.

18. Simple distillation
This is good for separating a liquid from a solution. For example, water can be separated from salty water by simple distillation. This method works because the liquid evaporates from the solution, but is then cooled and condensed into a separate container. The salt does not evaporate and so it stays behind.

20. Boiling and freezing points
Example
Petroleum contains gasoline, kerosene, fuel oil, and many useful other substances. When petroleum is heated different substances evaporate at different temperature, therefore each substance can be collected according to its boiling point. This process is called fractional distillation.

21. MAJOR FRACTIONS OF PETROLEUM
# of C atoms
Boiling Range (oC)
Uses
Gas
1-4
Fuel gas; starting material for plastics manufacture
Petroleum ether
5-6
30-60
Solvent, gasoline additives
Gasoline
5-12
40-200
Kerosene
11-16  
Diesel fuel, jet fuel, heating oil               
Heating oil 
15-18  
Industrial heating
Lubricating oil
17-24   
Over 350
Lubricants
Paraffin
20 and up
Solid residue
Candles, toiletries, wax paper
Asphalt
30 and up
Road surfacing

22. Evaporation
This is good for separating a soluble solid from a liquid (a soluble substance dissolves in water to form a solution). For example, copper sulphate crystals can be separated from copper sulphate solution using evaporation. Remember that it is the water that evaporates away, not the solution.

23. Solubility
Example
Sodium chloride NaCl(s) is soluble in water while calcium carbonate, CaCO3(s) is not. If a mixture of both is made water can be added to separate the two substances then the insoluble substance is filtered out of the mixture.

24. chromatography
chromatography is the process of separating substances from a mixture that rely on the differential affinities of substances for a gas or liquid mobile medium and for a stationary adsorbing medium through which they pass, such as paper, gelatin, or magnesia.
Example
Paper chromatography
When the end of a piece of paper is dipped into water the water molecules keep finding new places (polar regions) to stick to and so the water molecules climb up the paper being replaced by new water molecules below. Other molecules which might be dissolved in the water will also be carried along up the paper.

25. chromatography
A spot of dye is placed on the paper above the level of the water. As the water moves up, the dye molecules will move with it if they are more strongly attracted to the water molecules than to the paper molecules. If the dye molecules are more strongly attracted to the paper than to the water, they will move more slowly than the water or even not at all. What if the dye is a mixture? If two or more dyes have been mixed to form an ink, then they may move at different rates as the water moves up the paper. If this happens, they will separate and we can identify them.

26. Chromatography
This is good for separating dissolved substances that have different colours, such as inks and plant dyes. It works because some of the coloured substances dissolve in the liquid better than others, so they travel further up the paper.

27. Paper chromatography

28. TEST YOUR UNDERSTANDING
Which mixture can be separated by using the equipment shown below?
(1) NaCl(aq) and SiO2(s)  
(2) NaCl(aq) and C6H12O6(aq)  
(3) CO2(aq) and NaCl(aq) 
(4) CO2(aq) and C6H12O6(aq)

29. TEST YOUR UNDERSTANDING
When a mixture of water, sand, and salt is filtered, what passes through the filter paper?
(1) water, only (2) water and sand,only
(3) water and salt, only  (4) water, sand, and salt
  Which physical property makes it possible to separate the components of crude oil by means of distillation?
(1) melting point (2) conductivity
 (3) solubility  (4) boiling point

30. TEST YOUR UNDERSTANDING
At equilibrium, nitrogen, hydrogen, and ammonia gases form a mixture in a sealed container. The data table below gives some characteristics of these substances.
Describe how to separate ammonia from hydrogen and nitrogen.