Page 293 - Microsoft Word - LessonPlan-Overview.doc

Unit 8: Chemistry Page 18

should definitely try it! Use a 2:1
Polymers
ratio of cornstarch:water.) The
long molecular chains (polymers)
When you
are all tangled up when you
think of slugs,
scrunch them together (and the
snails, and
thing feels solid), but the polymers
puppy kisses,
are so slick that as soon as you
what texture
release the tension, they slide free
do you
(and drips between your fingers
imagine? Is it
like a liquid).
sticky, slithery, or slippery? Any
way you picture it, slime is just
Scientists call this a non-Newtonian
plain icky — and a perfect forum
fluid. You can also fill an empty
for learning about polymers.
water bottle or a plastic test tube
half-full with this stuff and cap it.
Imagine a plate of spaghetti. The
Notice that when you shake it
noodles slide around and don’t
hard, the slime turns into a solid
clump together, just like the long
and doesn’t slosh around the tube.
chains of molecules (called
When you rotate the tube slowly, it
polymers) that make up slime.
acts like a liquid.
They slide around without getting
tangled up. The pasta by itself
Reaction Rates
(fresh from the boiling water)
doesn’t hold together until you put
Chemical kinetics
the sauce on. Slime works the
is the study of the
same way. Long, spaghetti-like
speed that stuff
chains of molecules (called
happens on a
polymers) don’t clump together
molecular level
until you add the sauce -
that controls
something that cross-links the
reaction rate and the products we
molecule strands (polymer)
get out of the reaction. Why do we
together.
want to control the speed of a
reaction? Think of air pollution. If
If you've ever mixed
we could control the reaction rate
together cornstarch
of the ozone depletion, we could
and water, you know
control the problem better.
that you can get it to
be both a liquid and a solid at the
Chemical reactions can happen
same time. (If you haven't you
slowly (think of a boat on the

© 2010 Supercharged Science www.ScienceLearningSpace.com

293