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[SQUEAKING]

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[RUSTLING]

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[CLICKING]

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CLAIRE HALLORAN:
Today, we're going

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to be doing goody bag
1, atoms and reactions.

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Our objectives today
are to identify material

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based on its properties, observe
a simple chemical reaction,

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and identify the
limiting reagent,

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and estimate the number
of atoms in a real object.

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To do this goody bag, you'll
need vinegar, a plastic cup,

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a ruler, metal samples of
aluminum, copper, iron,

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magnesium, and tin,
but if you can only

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get copper and magnesium,
it will work, and a pipette.

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Some conceptual
questions to think about

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while you're doing
this goody bag are,

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how can we tell
different metals apart,

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and how can we count atoms
that are too small to see?

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First, we have five
samples of metal

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that we would like to identify
using their properties.

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The easiest to identify is
copper by its orange-ish color.

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Next, we're going
to try to find out

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which sample is iron by testing
how easy they are to bend.

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Iron will be the most
difficult to bend.

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So this sample bends very
easily just with my fingers,

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so it must not be iron.

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This sample is very
difficult. I can hardly

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get it to bend at
all with my fingers,

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and this sample also
bends fairly easily just

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using my fingers.

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So we know that this sample, the
hardest to bend, must be iron.

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Next, we're going to try
to compare the density

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of these different metals.

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So this metal feels the
heaviest and most dense.

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This one's feels
lighter, and this sample

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feels light as well.

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So we know that tin is
the most dense metal,

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so this sample must be tin.

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To identify which of
these samples is magnesium

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and which of them
is aluminum, we're

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going to test which one of
them reacts with vinegar.

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So we're going to place
each of these samples

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on the lid of our
plastic cup to make

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sure we don't spill
any of the vinegar

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and use our pipette to
put a drop of vinegar

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on each of the samples,
and the one that reacts

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will be magnesium, because
we know magnesium reacts

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with vinegar watch closely.

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It doesn't look like
we're getting any reaction

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from this metal, so it
must be the aluminum

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now, let's try the other.

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You can see that this material's
forming tiny bubbles after we

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put the vinegar on it,
so it must be magnesium.

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Those bubbles are hydrogen gas.

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Now, that the bubbling has
stopped on our magnesium,

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we note that the
reaction is over.

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There's still plenty
of magnesium left,

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so this indicates that
the acetic acid inside

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of the vinegar must be
the limiting reagent.

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Finally, we want to
estimate how many atoms

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are in our sample of copper.

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To do so, we're
going to use a ruler.

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Using our ruler, we can measure
the width and the height

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of this copper sample.

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So using the metric
side of our ruler,

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we align the 0 with the
edge of our material

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and see that it is about
13 millimeter wide and 25

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millimeter long.

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Today, we did goody bag 1.

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We identified our metal
samples based on their material

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properties, we observed
a simple reaction

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and identified the
limiting reagent,

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and we measured our copper to
estimate the number of atoms

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in our sample.