Chapter 9
Separating Mixtures and Solutions
How you would separate the following mixtures…
Salt water
Muddy water
Nuts and bolts
Iron filings and sand
Vegetable oil and sand
Vegetable oil and water
Salt and pepper
Discussion Question
“Are the components you have separated still mixtures, or are they pure? Why or why not?”
Separation Techniques
1. Mechanical Sorting:
Used to separate the parts of a mixture based on properties such as particle size.
Examples: floatation & magnetism
Magnetism
Floatation
-Floatation depends on the property of density.
For example
The density of rice in water is greater than the density of dust and dirt specks in water, so the
rice sinks to the bottom of the pot and the other materials float.
2. Filtration:
A common way to separate solid particles from a mixture:
- size of the holes in a filter permit some substances in the mixture (those with parts smaller
than the holes) to pass through, while trapping other substances (those with parts larger than
the holes).
The filters can have holes of varying sizes… small to microscopic.
3. Evaporation:
Change of state from a liquid to a gas.
Used to recover a solid solute from a solution.
4.Distillation:
Uses two changes of state:
evaporation and condensation.
It allows you to recover BOTH the solute and solvent from a solution.
5. Paper Chromatography:
Used to separate the colored substances in a mixture such as ink.
Used to separate the solvents in a mixture.
Works by comparing how fast dissolved substances are carried by a solvent through an
absorbent material.
Different substances move through an absorbent material at different rates, enabling them to
be distinguished from each other and identified.
Separation Techniques in the Home:
Colanders
Clothes dryers
Window screens
Coffee percolators
Salad spinners
Any others?
Distillation
Distillation: A Review
A method of separation that allows you to recover a single solute and a single solvent.
The mixture must boil so that the solvent can evaporate and that it is cooled so it can
condense back into a liquid.
Simple Distillation
Separates a single solute from its solvent
Fractional Distillation
Separates a mixture of liquids based on their varying boiling points.