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PHIL: The prize for the biggest
crystal is a lunch

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with John and the TAs at Legal
Seafood, which I'm personally

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very excited about.

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[MUSIC PLAYING]

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NARRATOR: Today the students are
going to learn a totally

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different technique,
recrystallization.

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PHIL: Pesticides,
pharmaceuticals, food

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colorings, and products where
they have to produce tons per

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year, recrystallization
is the key method.

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Yesterday you were working
with about 100

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megs of each compound.

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Today, you're going to be
working with 2 grams.

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NARRATOR: But there's more on
the line than just getting

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those 2 grams back.

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This is practice for next week's
crystal competition.

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If the students do well, they'll
have a better shot at

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winning a free lunch with
the teaching staff.

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The first step in a
recrystallization is to choose

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the right solvent.

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The students need a liquid that
will not dissolve the

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target molecule when it's cold,
but will dissolve it

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when it's hot.

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The students then dissolve the
sample in hot solvent and

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filter out any solid
impurities.

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Then they cool it down
in an ice bath.

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The target molecule should
crystallized out of solution

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forming a pure solid.

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The impurities should
stay in the liquid.

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ANTHONY: Fresh.

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IKE: Yep.

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That's how we want it.

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Crystal clear.

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NARRATOR: Ike, Ethan, and
Anthony are having

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no problems at all.

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ETHAN: Ain't nothing too hard
for an MIT chemist.

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NARRATOR: Hansol, Jason, and
Fred on the other hand--

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HANSOL: I made like two,
actually three mistakes today.

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JASON: I've made so many
stupid mistakes today.

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HANSOL: Yeah, I didn't realize
it would heat that fast.

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FRED: Um, it exploded all over
the side of my flask.

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HANSOL: And then it exploded,
so then I had to start over.

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PAUL: It started sputtering
out and actually

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it was kind of scary.

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Some of it almost like
hit me in the face.

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JASON: I've broken
a test tube.

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HANSOL: And then I put it
through a small funnel which

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was a total mistake.

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JASON: I put too much solvent
losing some product.

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HANSOL: The funnel,
I just dropped it.

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So--

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JASON: The yield on this
is almost nothing.

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NARRATOR: After filtering,
washing and drying, everyone

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eventually makes it to the
final step, weighing the

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purified crystals.

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Getting 90% yield is the goal.

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That would be 1.8 grams of
the original crystal.

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LEALIA: So far my yield
says 1.9 grams.

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So I don't know if that's right
because there is only

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supposed to be two grams.

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JULIE: That's probably not going
to be that good because

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that all I have.

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There were some problems with
filtering and then also

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noticed trying to put the stuff
in the beginning, I

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spilled it everywhere.

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YI-SHIUAN: Is it really pure?

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JULIE: 7%.

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LEALIA: 101% yield.

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JULIE: Good job.

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JASON: 3%.

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So besides 3% yield, my melting

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point's almost perfect.

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NARRATOR: For some today,
a good start.

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For others--

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JASON: 3% yield.

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You needed 90%.

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I only got 3%.

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NARRATOR: Not looking so
hot for next week.

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Tune in, and see how
it all unfolds.

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PHIL: Just make observations,
write down what could have

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went wrong, what you could
do differently next time.

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JASON: Not spill.

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Sleep more beforehand so
I don't make mistakes.

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Not spill.

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PHIL: Take your vitamins.

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JASON: Not be an idiot.

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I don't know.

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[MUSIC PLAYING]