WEBVTT

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[MUSIC PLAYING]

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PROFESSOR: Patience is a virtue.

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We all learned that
when we were young.

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It'll come into play during
our filtrations in this video.

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The process of
filtration is used

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to separate your solid
product from solvent

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or to remove impurities
from your solution.

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This video will discuss
three types of filtration,

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microscale filtration via
Pasteur pipet, gravity

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filtration, and finally,
vacuum filtration.

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First, let's address
microscale filtration.

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We'll be using the
Pasteur pipet to carry out

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this type of filtration.

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I bet you never thought you
could have this much fun

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on such a small scale.

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Here's how to prepare
your filter pipet.

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Here's a piece of cotton.

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Break off a small bit.

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Roll this into a small ball.

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The ball should be about
the size of the top opening

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of the pipet.

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Place the cotton ball there.

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You can use either copper
wire or another pipet

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to stuff down the cotton.

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With a few jabs, it should
be nicely wedged in there.

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You want to firmly pack it
down so it enjoys a snug

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fit between the wide portion
and the narrow portion

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of the pipet.

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But let's add something extra.

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As you can see,
here is the cotton,

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but sitting on top of
it, we've placed celite.

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What is it, you may ask?

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Celite is a very
fine powder used

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to filter very small particles.

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We'll be using it
in this filtration.

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Now for the setup.

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Here, we have the
mixture to be filtered.

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And here, we have our filter
pipet, which is securely

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clamped to a stand, and
we've placed a collection

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vial underneath it.

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Now it's time for filtration.

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Draw up some of the
mixture with another pipet.

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Transfer the mixture
to your filter pipet.

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Allow it to do
its filtering job.

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[MUSIC PLAYING]

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Look down at the tip
of the filter pipet.

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Can you see?

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Squint, if you must.

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The filtered liquid
should be draining out

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into your collection vial.

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[MUSIC PLAYING]

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All right, all right.

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I'll spare you the squinting.

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Look.

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Our once black mixture is
now clear when filtered.

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But what's that I hear?

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You're a bulb fiend?

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Or what's worse, you
just have no patience?

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If you insist on using the bulb
to expedite your filtration,

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then there are some
rules for its usage.

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When using the bulb,
don't push so eagerly

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that impurities get
pushed through the cotton

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or that the cotton
is pushed out itself.

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And once you begin,
never release the bulb

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since air, impurities,
or even the cotton

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could be sucked back up.

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Let's get back on track
and take care of rinsing.

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As you can see here,
there's residual mixture

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left in the flask.

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Rinse the flask with
solvent, allowing

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it to run down the sides and
collect any residual mixture.

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Draw up these washings
into the pipet

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and transfer them, adding the
washings to the filter pipet,

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allowing them to be
filtered themselves.

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You need to rinse the
flask and add its washings

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a total of three times.

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When the filtration's
all done, we'll

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have the filtered product.

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Here it is, the beauty.

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Free of impurities.

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But let's take one last
look at our filter pipet.

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Here it is after the filtration.

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As you can see, impurities have
collected on top of the celite.

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So that was microscale.

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Let's go macroscale
with gravity filtration.

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First, let's explore
chemistry origami

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while fluting our filter paper.

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Here's our goal.

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You should always
fold when fluting.

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Making a harsh crease
might cause filter paper

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to tear eventually.

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Let's get started.

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First, you want to
fold it in half.

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Open it up and fold
it in half once again,

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this time in the
opposite direction.

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You want to pinch the
bottom and push in, like so.

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Notice how it now
forms a sort of x.

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Open it slightly
and do the pinch

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and push move once again, this
time in the opposite direction.

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As you can see, you're
already halfway there.

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You should have
four main sections.

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Take one section and
separate it from the rest.

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Push in the crease, and fold
back the little triangles

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that form.

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You want to do the same thing
for the next three sections.

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Essentially, you're forming
two little triangles

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from one big one, like a
mother giving birth to twins.

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Isn't that great?

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You're halfway to a fully
fluted filter paper.

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Try saying that
three times fast.

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By the end of this, all the
folds should be alternating.

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This creates the fluted majesty.

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Don't worry.

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You'll get the hang of it.

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Aaa!

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You may be asking, why should
we even bother to flute?

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Well, it increases
the surface area

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of contact between the
mixture and the filter paper,

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therefore, a more
efficient filtration.

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Now for the setup.

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Here, we have our
mixture to be filtered,

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and here, we have
our collection flask.

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Into the flask,
place your funnel.

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It should be
appropriately sized.

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And into the funnel, place
the fluted filter paper.

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Don't you feel proud?

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Now that we're all set up,
it's time for filtration.

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Pour the mixture onto
the filter paper.

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Be sure not to pour too
much that it overflows.

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[MUSIC PLAYING]

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As the filtration progresses,
add more of the mixture.

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But remember, there's
always rinsing.

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Here, we can see the residual
mixture in the flask.

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Using a pipet, make sure to
rinse your flask with solvent,

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allowing it to
run down the sides

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and pick up the
residual mixture.

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Then add these washings
to the filter paper.

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Ah, but don't forget, you
want to rinse the filter paper

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with solvent as well.

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Use a pipet.

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Like always, you want to rinse
your flask and the filter paper

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three times each.

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When you think gravity's
done all that it can,

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it's time for
collecting the product.

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If you were aiming
for the solid product,

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take the filter paper
out of the funnel

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and place it on another piece of
filter paper or a watch glass,

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and allow the product
to dry overnight.

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But what if you have three
psets, a test tomorrow,

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a paper due the next day,
and your mixture just

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doesn't seem to understand
you're pressed for time?

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Well, then you have the
option of vacuum filtration.

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For vacuum filtration, you
can use either the Buchner

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or the Hirsch funnel, depending
on what you're filtering

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and how much there is to filter.

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Really, there's not much
difference between the two

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besides shape and size.

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Now for the setup.

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Here, we have our filter flask.

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Notice its
characteristic sidearm.

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Make sure the flask is
clamped firmly to a stand.

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When it's all put together,
the filter and funnel

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will make a top-heavy structure,
making it prone to fall.

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So a clamp is your best bet.

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And here is our Buchner funnel.

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If it doesn't already have
a rubber adapter, add one.

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Securely fit the
funnel and adapter

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into the top part of the flask.

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But what's that, you say?

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The fit between the funnel and
the flask isn't snug enough?

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Well, there's an alternative.

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Another type of rubber adapter.

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Notice its shape and size.

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And look in the middle there.

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There's a raised area.

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This raised area fits into
the mouth of the flask,

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as seen here.

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Push down so that the
flat side is on the top

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and there's a nice snug fit
at the top of the mouth.

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Then take your Buchner
funnel and securely fit it

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into the adapter.

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Regardless of the type
of adaptor you use,

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be sure to have a
snug fit before you

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proceed with your filtration.

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The piece of filter paper
should be large enough

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to cover the funnel space but
not fold up onto the sides.

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Now add the water
trap to the setup.

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Make sure it's firmly
clamped to the stand.

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It consists of a filter flask.

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Also, notice its sidearm.

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A rubber stopper.

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This can also be some
sort of glass stopper.

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And tubing.

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Attach one end of vacuum
tubing to the tube on the water

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trap and the other end to the
side arm of the filter flask.

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Then attach the side
arm of the water trap

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to the water aspirator
via more vacuum tubing.

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So at this point, you
might be wondering,

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what do the water aspirator
and water trap do anyway?

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When the water
aspirator is turned on,

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out comes a rush of water.

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This rush of water causes
suction in the tubing.

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This then suctions out
the air from the system.

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Consequently, a vacuum is
created in both the filter

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flask and the water trap.

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Now we can filter.

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When we finally finish, we'll
have to turn off the aspirator.

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This may cause water to
rush back into our system,

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and this could be
potentially bad.

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But look!

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Our water trap
prevents the water

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from entering our filter flask.

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And so luckily, our
filtrate is saved

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from any water contamination.

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Yay!

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This is why we love, and
more importantly use,

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the water trap.

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But what if you're using the
house vacuum line instead

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of the water aspirator?

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Well, the filter flask
sidearm should then

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be directly attached to the
house vacuum nozzle via tubing.

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Don't worry about any
intermediaries like the water

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trap.

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So now it's time for filtration.

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Turn on the water
aspirator at full force.

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The vacuum should suck
down the filter paper.

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Wet the filter
paper with solvent

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so that it sticks to
the base of the funnel.

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You don't want it
floating up later.

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Here's our mixture
to be filtered.

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Take the mixture and
pour it into the funnel,

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but make sure that
you pour the mixture

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into the middle of the funnel.

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[MUSIC PLAYING]

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Don't pour it in all at once.

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Pour in more of the mixture
as the filtration progresses.

00:14:34.600 --> 00:14:38.420
We can't forget that
rinsing, though.

00:14:38.420 --> 00:14:41.630
As usual, there's
residual mixture left.

00:14:41.630 --> 00:14:48.160
Rinse the flask with
solvent, allowing

00:14:48.160 --> 00:14:51.880
it to run down the sides and
pick up any residual mixture.

00:14:51.880 --> 00:14:54.280
And add these washings
to the filter flask.

00:14:59.850 --> 00:15:04.720
And remember to rinse the filter
paper with solvent as well.

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Round and round goes the pipet.

00:15:08.110 --> 00:15:10.810
You should rinse your
flask and the filter paper

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in the funnel three times each.

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Allow the filtration
to come to an end.

00:15:18.320 --> 00:15:21.170
Once you think it
has, then it's time

00:15:21.170 --> 00:15:22.820
for turning off the aspirator.

00:15:22.820 --> 00:15:26.710
[WARNING BEEPS]

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If you did not
attach a water trap,

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take tubing off before
turning off the aspirator,

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otherwise, water might
rush into your flask.

00:15:36.490 --> 00:15:40.100
So how about
collecting the product?

00:15:40.100 --> 00:15:42.230
If you were aiming
for the solid product,

00:15:42.230 --> 00:15:44.930
use a spatula or
some sort of tool

00:15:44.930 --> 00:15:48.770
to release the filter
paper from the funnel.

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Set it down on another piece of
filter paper or a watch glass,

00:15:52.940 --> 00:15:57.090
and allow the product
to dry overnight.

00:15:57.090 --> 00:16:00.330
So now, you're
finally all filtered.

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Now that you've got the skills,
go out and purify the world.

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Remember, this video
is intended to help

00:16:10.370 --> 00:16:13.250
you prepare for lab by
providing a demonstration

00:16:13.250 --> 00:16:15.980
of the proper
experimental technique.

00:16:15.980 --> 00:16:17.930
It is not intended
as a replacement

00:16:17.930 --> 00:16:21.980
for reading your lab manual
or the supplementary material.

00:16:21.980 --> 00:16:24.380
In order to become a
great experimentalist,

00:16:24.380 --> 00:16:26.810
it is important that you
understand both theory

00:16:26.810 --> 00:16:28.250
and technique.

00:16:28.250 --> 00:16:29.480
Now it's your turn.

00:16:29.480 --> 00:16:30.050
Good luck.

00:16:33.350 --> 00:16:35.500
[MUSIC PLAYING]