Physical Science 3.3 : Mixtures

Mixtures
Physical Science
Chapter 3.3

Objectives:
Describethree properties of mixtures.
Describefour methods of separating the parts of a mixture.
Analyzea solution in terms of its solute and solvent.
Explainhow concentration affects a solution.
Describethe particles in a suspension.
Explainhow a colloid differs from a solution and a suspension.
Bellringer
When you add sugar to coffee, tea, iced tea, or lemonade, the sugar disappears. What do you think happens to the sugar?

Properties of Mixtures
Mixture
combination of two or more substances that are not chemically combined
No Chemical Changes in a Mixture
So, each substance has the same chemical makeup it had before the mixture was formed.
Separating Mixtures Through Physical Methods
Mixtures can be separated by using physical changes.
Physical changes do not change the identities of the substances.

Salt dissolves in water
Magnet: separates mixture of metals from nonmetals.
Distillation:separates mixture based on boiling points
More than one mixture:
Takes more than one step.
Filtration: remove large solid from liquid.
Evaporation: remove dissolve solid from liquid
Pour mixture through filter
Centrifuge: separates mixture by densities of components
Evaporate water

The Ratio of Components in a Mixture
The components of a mixture do not need to be mixed in a definite ratio.
Example, granite is a mixture of three minerals.
Feldspar - pink
Mica - black
Quartz - colorless

Solutions
mixture that appears to be a single substance.
Dissolving
Process in which particles of substances separate and spread evenly throughout a mixture
solute
the substance that is dissolved.
solvent
the substance in which the solute is dissolved

Examples
Liquid solutions
soft drinks
Gasoline
tap water
Gas solutions
Air
Solid Solutions
Steel
Brass
Gold in jewelry
Alloys
solid solutions of metals or nonmetals dissolved in metals.

Particles in Solutions
Particles in solutions are so small that they never settle out.
Cannot be removed by filtering.
Particles are so small that they don’t even scatter light.

Concentrations of Solutions
A measure of the amount of solute dissolved in a solvent.
Concentrated or Dilute?
Concentrate: a lot of solute in solution
Dilute: small amount of solute in solution

Solubility
the ability of a solute to dissolve in a solvent at a certain temperature
The solubility of most solids in water increases with temperature.

Dissolving Gases in Liquids
Gases become less soluble in liquids as the temperature is raised.
Dissolving Solids Faster in Liquids
3 Ways to make a solid dissolve faster:
Mixing the solution
Heating the solution
Crushing the solute into smaller particles.

Suspensions
a mixture in which particles of a material are dispersed throughout a liquid or a gas but are large enough that they settle out.
The particles are large enough to scatter or block light.
Can be separated by passing it through a filter.

Colloids
A mixture in which the particles are dispersed throughout but are not heavy enough to settle out.
Particles in a colloid are large enough to scatter light.
Cannot be separated by passing it through a filter.

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Physical Science 3.3 : Mixtures

by Chris Foltz on Mar 30, 2010

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