For more on Mixtures (Solutions, Suspensions, Emulsions,
suspension is a mixture between two substances, one of which is finely
divided and dispersed in the other. Common suspensions include sand in water,
dust in air, and droplets of oil in air. Particles in a suspension are larger
than those in a solutions; they are visible under a microscope and can often be
seen with the naked eye. Particles in a suspension will settle out if the suspension
is allowed to stand undisturbed. Many particles of a suspension can be separated
through a filter. An example of a simple suspension would be flour in water, or
sand in water.
colloid is a type of mixture intermediate between a homogeneous mixture (also
called a solution) and a heterogeneous mixture with
properties also intermediate between the two.
particles in a colloid can be solid, liquid or bubbles of gas. The medium that
they are suspended in can be a solid, liquid or gas (although gas colloids cannot
be suspended in gas).The particles are approximately 10 to 10,000 angstroms in
size and generally cannot be filtered, or settled out in an easy manner. Colloids
may be colored or translucent because of the Tyndall effect, which is the scattering
of light by particles in the colloid. Colloid particles may be seen in a beam
of light such as dust in air in a "shaft" of sunlight.
movement may be used to distinguish between solutions and colloids. Brownian
motion is the random movement of colloidal particles suspended in a liquid or
gas, caused by collisions with molecules of the surrounding medium. The
particles in solutions and colloids are in constant motion. However colloid particles
are large enough to be observed and are small enough to still be affect by the
random molecular collisions. Colloid particles resist settling rapidly to the
bottom of a vessel due to Brownian motion.
are a type of colloid
are an example of colloids composed of tiny particles suspended in another immiscible
(unmixable) material. An emulsion is a suspension of two liquids that usually
do not mix together. These liquids that do not mix are said to be immiscible.
An example would be oil and water. If you mix oil and water and shake them a cloudy
suspension is formed. Let the mixture rest and the oil and water will separate.
emulsifying agent (emulsifier) is any substance that keeps the parts of
an emulsion mixed together. For example if we mix oil and water a suspension will
form that over time separates. But now, if we add a few drops and shake the mixture
the oil and water will stay mixed much longer.
Examples of emulsions include butter and margarine, and mayonnaise.
See also HYDROCOLLOIDS
gases are soluble)
Examples: Fog, Mist
Examples: smoke, dust
Milk, Mayonnaise, hand cream
Paint, pigmented ink, blood, Milk of Magnesia
Examples: Aerogel, Styrofoam, pumice
Examples: ruby glass