A mixture forms when two or more substances are combined such that each substance retains its own chemical identity. Everywhere around us are made up of mixtures. We can see them in nature, along the surface of the earth, in the oceans and in the foods we eat. There are infinite numbers of mixtures that can be combined into homogeneous or heterogeneous.
3. Mixture
A mixture forms when two or more substances
are combined such that each substance retains its
own chemical identity. Everywhere around us are
made up of mixtures. We can see them in nature,
along the surface of the earth, in the oceans and
in the foods we eat. There are infinite numbers of
mixtures that can be combined into
homogeneous or heterogeneous.
8. Solute
ď‚— substance in the
smallest amount
ď‚—the chemical
dissolved in a
solution.
ď‚—In this case, acrylic
paint is the solute
and water is the
solvent.
9. Examples of Solutes
ď‚— Salt in water: Salt is the solute that dissolves
in water as the solvent to form a saline
solution.
ď‚— Water vapor is considered a solute in air,
since nitrogen and oxygen are present in much
larger concentration levels in the gas.
ď‚— Solutes and solvents may also be applied to
alloys and solid solutions. Carbon may be
considered a solute in steel.
10. Solvent
ď‚—dissolving; effecting a
solution.
ď‚—a substance in the
larger amount,
usually a liquid, that
dissolves or is capable
of dissolving
ď‚— the component of a
solution present in
greater amount.
11. Solvation Process
ď‚—the process of attraction and
association of molecules of a
solvent with molecules or ions of a
solute. As ions dissolve in a
solvent, they spread out and
become surrounded by solvent
molecules.
ď‚—Solvation is an important role of a
solvent in the corrosion process.
ď‚—Changes in solvent composition
alter solvation properties. The
solubility of metals from solvent to
solvent significantly varies due to
differences in solvation properties. A sodium ion solvated by water molecules
15. Types of Solutions according to Solubility of Solutes
1) Saturated solution contains the maximum amount of solute in a given
solvent at a specific temperature.
ď‚—a solution in equilibrium with undissolved solute
2) Unsaturated solution contains less solute than it has the capacity to
dissolve
ď‚—a solution not in equilibrium with dissolved solute more solute can be
dissolved
3) Supersaturated solution contains more solute than is present in a
saturated solution
ď‚—unstable solution
ď‚—prep: heat solution to high temperature, then slowly cool
16. 1) Temperature - Solubility of solute increases with temperature
ď‚—Easier to dissolve sugar in hot milk than in cold milk
2) Size of solute particles-smaller the size greater the solubility of
solute
ď‚—Easier to dissolve powdered sugar in coffee then granules of
sugar
3) Mechanical Stirring-solubility of solute increases with
mechanical stirring.
ď‚—Sugar dissolves faster with faster stirring with a spoon or
stirrer.
Factors Affecting the Solubility of a Solid Solute
17. Suspensions
ď‚—a heterogeneous mixture in which the solute particles do not dissolve
but get suspended throughout the bulk of the medium.
ď‚—The particles in suspensions are larger than those found in solutions.
ď‚—Components of a suspension can be evenly distributed by a mechanical
means, like by shaking the contents, but the components will settle out.
18. Examples of Suspensions
ď‚—mercury shaken in oil
ď‚—oil shaken in water
ď‚—powdered chalk in water
ď‚—dust in air
ď‚—soot in air
ď‚—Mixing or shaking needs to occur to form a
suspension. Given time, suspensions usually
separate on their own.
19. Colloids
ď‚—Particles intermediate in size
between those found in
solutions and suspensions can be
mixed such that they remain
evenly distributed without
settling out. These particles
range in size from 10-8
 to 10-6
 m
in size and are termed colloidal
particles or colloids. The
mixture they form is
called colloidal dispersion. A
colloidal dispersion consists of
colloids in a dispersing medium.
20. Colloidal Dispersion
ď‚—Mixture formed by colloids in a dispersing medium. Liquids,
solids, and gasses all may be mixed to form colloidal
dispersions.
ď‚—Dispersions:
1. Aerosols: solid or liquid particles in a gas.
2. Sols: solid particles in a liquid.
3. Emulsions: liquid particles in a liquid.
4. Gels: liquids in solid.
21. Examples of Colloids
ď‚—Aerosols: fog, insecticide spray, clouds, smoke and dust
ď‚—Foams: whipped cream, and shaving cream
ď‚—Solid Foams: marshmallows and Styrofoam
ď‚—Emulsions: milk, mayonnaise and lotion
ď‚—Gels: gelatin, butter and jelly
ď‚—Sols: ink, rubber, liquid detergent and shampoo
ď‚—Solid Sols: pearl, gemstones, some colored glass and
some alloys
22. How To Differentiate a Colloid From a Solution or Suspension
ď‚—Components of a suspension
separate over time. Solutions and
colloids don't separate.
ď‚—If you shine a beam of light into a
colloid, it displays the Tyndall
Effect, which makes the beam of
light visible in the colloid because
light is scattered by the particles.
An example of the Tyndall effect
is the visibility of light from car
headlamps through fog.