>> host: You've had
some time now to plan your
engineering design challenge.
Were you successful?
Did you show your teacher
how you decided to
separate the materials?
Let's get back to our classroom
to compare your results
to those of our students.
>> professor: Team one,
how did you do with this
engineering design challenge?
>> student: Our plan was
to do the separation
one step at a time.
We don't know what the big
pellets are made out of,
but we noticed that the magnets
didn't affect them.
We found out that the magnets
pulled out the dark particles,
so we guessed that
they were iron.
>> student: So we pushed
the magnets around in the sand
to get the iron out.
I think we got all of it.
We just picked up the bigger
metal pellets with our fingers.
>> professor: Okay.
Those big pellets
were made of zinc,
and there are other ways
to separate zinc
than using your fingers.
But for now,
their method worked.
Anything else?
>> student: Sure.
The styrofoam floated on top,
so we used the cheesecloth
to separate that.
>> student: That meant
the beaker had water, sand,
and a dissolved white powder.
Maybe sugar or salt?
We poured the water
into the other beaker,
leaving most of
the wet sand behind.
>> student: We put the beaker
of water on top of the hot plate
to evaporate the water out,
and we saw what looks like salt
crystallized on the sides
of the beaker.
>> professor: Good thinking.
Let's count how many items
you separated.
Zinc pellets, iron filings,
styrofoam, salt, sand,
and some water,
and the rest of the water
evaporated into the air.
Good job.
And you did this
in how many steps?
>> student: 1, 2, 3,
4, 5, 6.
Six steps.
>> professor: Okay, now,
let's hear from the other team.
>> student: We tried some
things that were different,
and some of the same things.
We pulled out the big zinc
pellets with our fingers,
and we added water to get
the styrofoam pieces out, too.
>> student: We decided to
tape the magnets on the tube,
and then pour the iron,
sand and salt mixture
down the tube
to trap the iron filings
on the way down.
>> professor: Did it work?
>> student: I don't think
we got all the iron out.
Then we fixed the ring stand,
so all the water would
pour through a funnel that
we lined with this cloth.
>> student: The cloth seemed
to catch most of the sand,
but some of the sand
got stuck in the tube.
To separate the salt
and the water, we heated
the water on the hot plate,
so the water evaporated,
leaving the salt behind.
>> student: We tried to
catch the water using
a piece of glass,
so the water would condense.
The water dripped a lot,
so we had a hard time
getting the glass turned
so we could catch
the water in a beaker.
>> professor: That was
a good try.
You separated zinc, styrofoam,
iron, sand, salt and water.
You separated five materials.
You now have a chance
to revise and design
and try again tomorrow,
when I'll grade your work
with the engineering design
challenge rubric.
Plan together, and remember,
you can change your procedures
as long as you only use
the equipment that's here.
Get together with your partner
and start revising your plan.
>> host: Our teams did
a really great job of
separating all those materials.
Now they have a chance to
redesign their procedures,
just like scientists
and engineers do.
You should try this challenge
again yourself,
and see if you can develop
a better separation method
on your second try.
You now know about
physical and chemical
properties of matter,
physical and chemical changes,
phase changes of solids,
liquids and gasses, mixtures,
and common separation methods.
And you got to show off
your creativity with an
engineering design challenge.
But before we wrap this unit up,
let's go back to where
we started for a minute,
the very top of this unit,
when I mentioned that
the water molecules
you're drinking today
may be the same molecules
that were in your toilet
a few weeks ago.
And for a better
understanding of that,
I spoke with Stan Brinkley,
who's a treatment division
manager at the Cobb County
Marietta Water Authority.
Thank you for joining us, Stan.
Uh, now tell us what it is
you do at the Cobb County
Marietta Water Authority.
>> I'm the plant manager
of the Quarles Water
Treatment Plant.
We're an 86 million gallon a day
conventional treatment plant,
and we supply most of the water
for Cobb County.
>> host: Great.
And how did you get interested
in this line of work?
>> Well, I actually, uh,
my first promotion from
an operator to the lab,
was because I had
had high school chemistry.
>> host: Nice.
So, tell us about how water
is delivered to plants that
purify our drinking water.
>> Well, in our case,
we take the water out of
the Chattahoochee River
and, uh, bring it to
the plant to treat it.
Uh, it's a four-step process.
Conventional treatment.
The first step is coagulation.
And we add a chemical
to the water that
actually coagulates
and takes all the dirt particles
out of the water
and separates them.
Uh, the second step of that
is flocculation.
In that step, the particles
that we have separated,
we actually build them up
to a bigger mass,
so that they will actually
have weight and settle out.
And the next step,
which is sedimentation.
So, in the sedimentation basin,
over time,
all those particles
that we've formed
then settle out and fall
to the bottom of the basin.
We have clean water that comes
then to the, uh, filters
to be filtered.
>> host: Our students just
did a filtration exercise,
so they should be familiar
with that concept.
>> That's right.
So, after the filters,
it filters any of
the suspended matter out,
and the oxidized, uh, metals
and things out of the water.
So, once it gets through that,
it-it's clean drinking water.
>> host: Great.
>> And then we add chlorine
to the water to disinfect it,
so that it's safe to-to drink.
>> host: Now, tell us about
the tests that are done
at your plant to make sure
it's safe to drink in our homes.
>> Well, our plant operators
are there 24 hours a day,
7 days a week, and every hour,
they're performing
chemical tests on the water.
They check for
chlorine residuals,
they check for Ph,
they check for iron manganese,
they check for fluoride residual
that helps the-the dental
in children.
So, there's somebody there
24 hours a day, 7 days a week,
to ensure that the water's
safe to drink.
>> host: So that is good,
clean water?
>> Good, clean water.
>> host: That's great.
Now, let's talk a little
about-about waste water,
because that's different.
Now how is waste water delivered
to treatment facilities?
>> Well, waste water is
collected at the homes and
it goes to a waste water plant.
And there, they do
a different process,
but they basically take
all the solids and material
out of the water,
and the water leaves that plant,
then goes into
a receiving stream,
and goes back into a stream
or a river or something.
Back into the natural
watershed.
>> host: Now, is that--
Is-is the, say,
rain water from the street
treated the same way that
waste water from our homes is?
>> No.
Typically, the rain water goes
into what's called storm water.
>> host: Okay.
>> And it just pipes that water
into a creek or something,
and it runs back into the river
and enters the waterway
that way.
>> host: Okay.
Now, a lot of people,
they drink bottled water,
because they feel like
it-it's safer or whatever.
Uh, what do you
think about that?
>> Well, all the water from
the water treatment plants,
uh, passes all the
federal regulations.
So, it is perfectly
safe to drink,
and there's no reason not to
be drinking your tap water.
>> host: And we can't say that
about bottled water,
necessarily.
>> Well, bottled water's
not regulated by anybody.
>> host: So, no comment
about bottled water?
But definitely tap water
is good to go.
>> Tap water is good to go.
>> host: Excellent.
And-and just goes to show that
Chemistry matters, right?
>> That's right.
>> host: Great.
Well, thank you so much
for joining us.
A lot of great information.
>> Thank you.
>> host: I hope you enjoyed
this "Introduction to Matter."
Join me for Unit 3 of our
"Chemistry Matters" series,
"Atomic Structure."