Video Transcript
Which of the following substances
or phenomena is an example of a solid aerosol, a solid dispersed through a gas? (A) Mist, (B) fog, (C) paint, (D)
air, or (E) smoke.
The key phrase in the question is
solid aerosol, which, thankfully, has already been defined. It’s a solid dispersed through a
gas. Dispersed here means spread
out. Here we have a box that contains a
lump of solid surrounded by gas. The solid is concentrated in one
lump. It’s not dispersed. Instead, we’re looking for tiny
particles of solid spread throughout the gas.
Now, let’s look at our five options
and see which one matches. Mist consists of fine droplets of
water suspended in air, while fog is exactly the same thing but much denser, so you
can’t see as far. Water under these conditions will
be a liquid not a solid. So we’re dealing with a liquid
aerosol and not a solid aerosol, so these are not correct answers. Meanwhile, paints usually consist
of solid particles of pigment suspended in oil or water. So paints are solid–liquid
mixtures, and they may be colloids or suspensions. Either way, the dispersion medium
for paint is not a gas. It’s a liquid, so paint is not a
correct answer.
The fourth option, air, is a
mixture of many different gases. So we consider this a gas mixture,
although you could call it a gas solution because there’s a lot more nitrogen than
the other gases. Air is not a correct answer because
there’s no solid dispersed through it. We’d have to have dusty air or
smoky air for it to work. And lastly, we have smoke, which
consists of fine particles produced from combustion dispersed in air. So out of these five options, the
only one that’s an example of a solid aerosol, which is a solid dispersed through a
gas, is smoke.
