For experiment two, the first thing I want
to point out is, again, our safety precautions. I have my hair tied back. I’m wearing my safety
goggles. Even though I wear regular eyeglasses, I have to wear my safety glasses over my eyeglasses. And I’m wearing some sort of protective glove,
whether it’s nitrile or latex. In this case, I’m wearing nitrile. We’re going to be using–
I’m going to be using acetone and cyclohexane. And so this provides a little bit better protection
than the latex. So for experiment two, we’re going to be identifying
some unknowns based on physical and chemical properties. First, we’re going to describe
the physical properties, whether it’s a liquid, solid, if it has any color, whether it’s clear
or opaque. Another thing we’re going to record is the smell. So as chemists, we have a special way of determining
the smell. We don’t want to stick our face in the beaker, especially if it’s something
like sulfuric acid that can do some damage. So what we do is called wafting. And so we’ll
hold the beaker in front of our face and sniff as we’re waving the fumes towards our nose. Now, this one I can smell right away. This
one smells like nail polish, so I know that’s acetone. This one doesn’t smell like anything,
so I can’t determine based on the smell what it is. So that’s one of the things that we’re
going to ascertain in this experiment, is what is the smell. Another thing we’re going to do is the flammability
test. So I’m going to take my pipette. I’m going to treat every liquid as though it’s
flammable. And I want to take less than half a mill. This is a graduated pipette, so that I can
tell the volume. And there’s a dial at the top. I want to make sure my tip is immersed
in the liquid before I scroll the dial. I’m going to transfer that. I’m going to move these larger amounts of
liquid away, because again, I want to treat them all as though they are flammable. I’m
going to light my splint here. It’s a good reason to have your hair tied back whenever
you’re dealing with open flame. And then I’m really carefully going to lower
this down. If it’s flammable, even the fumes will catch fire. And it is, so I’ve taken
away the source of the flame and it’s still burning. So this is an example of a flammable
liquid. Again, I want to keep my match pack away. So I can test another liquid for flammability.
Again, I’m going to treat all of these as though they are flammable. So I’m going to
take less than half a mill. If I have too much volume, what can happen is I’ll get a
really big flame, and that’s too dangerous. I’m going to move my larger source of liquid
away, because again, I’m going to treat them like they are all flammable. I’m going to
light my splint again. I’m going to lower it into my bowl. In fact, this put the fire
out, so the second liquid that I used is not flammable. One of the other things that will determine
is miscibility. And this is really like a solubility for liquids. In our lab, we’re
not going to have you use your pipettes to remove your reagents. We’re just going to
pour a small amount into a beaker, and then we’ll transfer from that beaker. This prevents
contamination of our reagent bottles. So to test if something is miscible, I’m not
really concerned about measuring it. I’m just going to add enough that I can see some aliquot
into the test tube. You can use the pipette that for this. Or you can just pour it in. I’m going to add my second liquid. What I’m
looking for here is whether they mix completely or whether I see two distinct layers. So I’m
going to pour it in slowly. All right, so this is an example of immiscible
liquids– liquids that do not mix together completely. I can tell that because there’s
a distinct layer separating the two liquids. Let’s try another example. Again, I’m not really concerned with measuring
here. I just want to combine enough to see. So now, I’m going to mix different samples.
And again, I want to see if they mix completely– if they are miscible– or if I see a distinct
layer. This is an example of miscible liquids, because
I don’t see any distinct layer. And you can see kind of like a strain, like little wavy
lines as they’re mixing together. But after they are combined, I don’t see a distinct
layer. So this is an example of immiscible liquids.
And this is an example of miscible liquids. These are just a few of the techniques that
you’ll use in experiment two.