Video Transcript
Colloids consist of two phases: a
particulate phase and the state of matter these particles are spread between. What names are given to these two
phases?
A colloid is a type of mixture
where small particles of one substance are suspended and distributed throughout a
continuous medium. Their composition often looks
homogeneous, but in fact it is a heterogeneous mixture, meaning that the material is
not even throughout. And this can be observed by
examining a colloid under a light microscope. Here, we find the average particle
size of the particular phase tends to be about one to 1000 nanometers in
diameter.
One example of a heterogeneous
colloid is in whipped cream. If you’ve ever gotten a jar of
whipped cream from the store, you’ll notice that there are two layers. There’s a solid layer on top, made
up mostly of lipids and fats. And on the bottom is a liquid
layer, made up mostly of water and water-soluble components. But once enough mechanical stirring
has been applied, we end up with a colloid that’s much more commonly known as
whipped cream, where the liquid and solid layers from before are now
indistinguishable.
Now to answer this question, let’s
revisit the solid and liquid phase that make up this colloid. In this example, the solid layer,
made up of lipids, is also known as the particulate phase. And after enough mechanical
stirring is applied, the solid particulate phase becomes evenly distributed
throughout the liquid phase. And in any colloid, the particulate
phase is also known as the dispersed phase, which is the substance that is evenly
distributed throughout a continuous or dispersion medium.
In the example of whipped cream,
the dispersed phase is spread throughout a liquid phase, which in this colloid is
known as the dispersion medium. The dispersion medium is the phase
or medium that a substance, known as the dispersed phase, is evenly distributed
into. With this in mind, we can revisit
the question. Colloids consist of two phases: a
particulate phase and the state of matter these particles are spread between. What names are given to these two
phases? And the correct answer is dispersed
phase and dispersion medium.
