Name
Elements, Compounds, and Mixtures
Heterogenous Mixtures
In a heterogenous mixture, the substances being combined are not
distributed evenly, and pockets or layers of the individual substances exist.
Two types of heterogenous mixtures are suspensions and colloids.
A suspension is a liquid is mixed with a solid. Instead of dissolving when
mixed, the particles remain “suspended” throughout the liquid and can
easily be seen with the naked eye. If a suspension is left alone long
enough, the solid particles separate from the liquid and settle. This
happens because the particles in a suspension are large, and they settle
due to the effect of gravity. Some common examples of suspensions are
water and sand, chalk and water, muddy water, flour and water, a
mixture of dust particles and air, and fog.
A colloid is a type of mixture in which tiny particles of one substance are
distributed uniformly throughout another substance. A colloid is similar to a
solution, except that instead of one substance dissolving into another, the
particles of one substance are suspended throughout the other. A colloid
differs from a suspension in that the suspended particles stay suspended
indefinitely and do not separate and settle. The particles in a colloid are
somewhere between the size of particles in a suspension and particles in a
solution. Unlike with suspensions, the suspended particles cannot be seen
with the naked eye, but only with a light microscope. Milk is an example
of a colloid, since it is a mixture of liquid fat globules suspended in water.
Another common colloid with which you are probably familiar is Jello.
Jello is a colloid of gelatin particles suspended in water.
Suspensions and colloids differ in other ways, too.
Particles in a suspension can be separated using
a filter, but this is not the case for colloids. While
colloids can scatter light, suspensions are not
able to transmit light.
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