Video Transcript
Which of the following is not a
difference between a solution and a colloid mixture? (A) Particles in solutions are
smaller in size than those in colloids. (B) Colloids exhibit the Tyndall
effect, while solutions do not. (C) Solutions are homogeneous
mixtures, while colloids are typically heterogeneous. (D) A solution consists of a solute
and a solvent, while a colloid consists of a dispersed phase and a dispersion
medium. Or (E) particles in colloids can be
separated by simple filtration.
Let’s start by recalling some of
the characteristics of solutions and colloids. This will allow us to go through
each of the statements and decide which is not a difference between a solution and a
colloid.
Solutions are homogeneous mixtures,
and they are composed of a solute that is fully dissolved in a solvent. For particles to fully dissolve,
they have to become quite small. And the solute particle’s size in
solutions is between 0.01 to one nanometers. And the solvation of the solute
into such small particle sizes has a few effects on the properties. For example, the solute cannot be
filtered and separated from the solvent, and they are also fully transparent.
When examining colloids, we find
that they are heterogeneous mixtures with partially dissolved and partially
suspended particles. And they are composed of a
dispersed phase in dispersion medium. The particles in a colloid do not
fully dissolve and are therefore slightly larger than we see in suspensions:
typically between one and 1000 nanometers. Although the particles are larger
than in suspensions, the dispersed phase of colloids still cannot be filtered and
separated. However, unlike suspensions,
colloids are typically opaque because not all of the evenly distributed particles
are solvated.
And now, let’s take a look at the
Tyndall effect, which is the scattering of light that occurs when it passes through
a colloid or fine suspension. So, according to the Tyndall
effect, solutions have particle sizes that are so small that light does not
significantly scatter when it passes through. This lack of scattering has the
effect that we don’t see a beam of light as it passes through a solution. Colloids, on the other hand, have
much larger particle sizes than those of solutions. And so, as you pass a beam of light
through a colloid, there’s significant light scattering. This means that a beam of light is
very visible as it passes through.
And now with all of this
information, let’s revisit the question. Which of the following is not a
difference between a solution and a colloid? And as you can see, there’s only
one listed characteristic that is consistent between a colloid and a solution. And so, we can correctly choose
answer choice (E). Particles in colloids can be
separated by simple filtration.
