>> host: Welcome back
to "Chemistry Matters" Unit 9,
our Kinetics and Gases Unit.
We've been working
on the development
of our own airbag,
based on the reaction
between acetic acid
and sodium bicarbonate.
Have you determined
the optimum conditions
for your model airbag?
Let's go back to our classroom
so you can compare
your experimental results
to those of our students.
>> professor: It looks
like everyone's finished
collecting and analyzing data
for their model airbags.
I saw a lot of inflated bags
and heard a few bags
explode too.
I'm looking forward to
hearing about your results.
Who'd like to present
their data first?
>> student: We will.
We tested four different
amounts of vinegar
and baking soda.
We started with 2 grams
of baking soda
and 30 milliliters of vinegar,
because that's about
how much we calculated
we needed to fill the bag.
>> student: But then
we remembered you saying
that no reaction
is 100% efficient,
so we figured we'd
probably need more than
what we calculated.
>> student: So we increased
the baking soda by 1 gram
at a time.
Our original plan was
to increase baking soda
ten percent at a time,
but we found that increasing
by 1 gram at a time
was much easier.
>> student: And we kept
the ratio of vinegar
and baking soda the same
in each trial.
>> professor: I like how
you organized your data.
It's easy to see what you did.
What were your results
and conclusions?
>> student: Four grams
of baking soda
and 60 milliliters of vinegar
made the best model airbag.
That's almost twice as much
baking soda and vinegar
as we calculated
using stoichiometry.
>> student: Right.
That's probably because
of what we learned earlier
about the reaction
not being 100% efficient.
>> student: The bag inflated
the fastest and was inflated
so much we thought it would
burst, but it didn't.
>> student: Yeah, but when
we used 5 grams of baking soda,
the bag did burst open!
>> professor: Can you explain
why you think that more
baking soda and vinegar
caused the reaction
to go more quickly?
Try to use what we've learned
from the Collision Theory
and the Kinetic Molecular Theory
to support your answer.
>> student: Well...
more reactants means
more collisions,
which means more carbon dioxide
is made in the same
amount of time.
>> student: So the rate
of carbon dioxide production
increases with more reactants.
>> professor: Nice work,
Dory and Colin.
Let's see what the other team
learned from their experiment.
>> student: We started
with the same amounts:
2 grams of baking soda
and 30 milliliters of vinegar.
That didn't fill up
our airbag either.
But instead of increasing
vinegar and baking soda
at the same time,
we only increased
one variable at a time.
>> student: The combination
that filled the bag
completely and the fastest
was 5 grams of baking soda
and 40 milliliters of vinegar.
If we used 6 grams
of baking soda,
the bag popped open.
>> professor: Your results
are pretty close
to the other team's results.
The amounts they found
worked the best were
4 grams of baking soda
and 60 grams of vinegar.
>> student: Whoa!
That's a lot more vinegar
than we used!
>> student: We kept
an equal number of moles
of the reactants.
You used a lot more
moles of baking soda
than moles of vinegar.
>> professor: That's
a good observation of
a key difference, Dory.
Kayla and Bella had
a limiting reactant
in most of their trials.
Can you explain what
your reasoning was for doing
that Kayla and Bella?
>> student: We were trying
to keep vinegar
the limiting reactant
so it would get used up
and make less of a mess.
>> student: Yeah,
but towards the end,
we realized that we needed
to add a little more vinegar
to get all the baking soda
to dissolve.
>> professor: That's a great
idea to minimize leftover
reactants, and in fact,
that's the goal for
an automobile airbag.
I'm impressed that you kept
practicality in mind.
I also notice that Kayla
and Bella's times were shorter
than Dory and Colin's times.
Why do you think that might be?
>> student: We shook our bag
while it reacted, which I
think made it go faster.
>> professor: That's a very
good possibility, Bella.
The rate of a reaction
is increased with increased
agitation, as you know
from the Collision Theory.
Both teams have done
an excellent job creating
a model airbag.
You can continue with
more trials, of course.
But notice that you've
narrowed down the range
of values for the reactants
that make this size airbag
work the best.
You've successfully optimized
the reaction, and you recognize
when the reaction has
a limiting reactant.
Well done!
>> host: That was a fascinating
engineering-design challenge.
As you can imagine,
there are a lot more constraints
when developing an actual
airbag for automobiles.
Safety, speed, and cost are
all important considerations.
Some of you may want
to continue exploring this
engineering-design challenge
by identifying
other environmentally
friendly alternatives.
In any case, I hope you've
gotten an idea of the
complexity that's involved
in working with kinetics
and gasses.
To that end, I had a chance
to speak recently with someone
who uses this knowledge
in her job everyday.
And a pretty cool job it is!
Lea Merriwhether is
a senior lab technician
at the Georgia Aquarium,
where she monitors
water quality for all
of the Georgia Aquarium's
different habitats.
Lea, thank you so much
for joining us today
on "Chemistry Matters."
>> Lea Merriwhether: Thank you
for having me.
>> host: Now, you're at
the Georgia Aquarium.
What do you do there?
>> Lea: I'm senior
water quality tech,
and I'm responsible
for testing all
the exhibit water
from every system.
>> host: That's a big job.
It's a big place.
And how long have you
been there?
>> Lea: I've been there
about nine years.
>> host: Wonderful.
And the Georgia Aquarium,
for those who haven't been,
it's home to a whole lot
of animals.
There's a lot of fish
and other animals there.
And their natural habitats
are very varied.
Some of them come from
sea water habitats.
Some of them come from
fresh water habitats.
That's a lot of
different habitats you
all have to maintain.
I imagine you use Chemistry
all the time.
>> Lea: Yes, we do.
Here in Atlanta, the aquarium
is a closed system,
so we have to mimic
the systems that these species
are coming from,
whether it be sea, sea water,
or fresh water,
so with the sea water,
we use a product called
Instant Ocean to get that,
to create that ocean feel.
>> host: Nice.
And you probably have
to run a lot of tests
for different materials.
Tell us about some of the
materials that you test for
in the water on a daily basis.
>> Lea: We, uh, test
for pH, salinity, ammonia,
nitrite, uh, copper,
phosphate, iodine, alkalinity.
>> host: That's a lot to manage.
How do you manage all that?
How do you get those reports
and know how to respond to them?
>> Lea: Uh, we keep a system
of tracks, which is
an animal record system,
so for one system,
it g-give us-- it'll graph
a readout of everything,
all the pHes,
all the salinities,
all the ammonias,
all the nitrites,
all in one page.
>> host: It's a little like
my medical records, but for
the fish and their environment.
>> Lea: Correct.
>> host: Nice. And can you
use, then, that information
that you receive
to compare to other readouts
you've had in the past?
>> Lea: Oh, yeah, it can
go back at least five years.
>> host: Nice.
>> Lea: Um, and based off
of the daily numbers, the,
uh, biologists will write up
chemical additions.
>> host: And when you
get those readouts, how do
you respond if something
needs to be tweaked
in the system?
>> Lea: We, uh, have a set
of gallons in terms
of our parameters,
and we, uh, we can add
sodium bicarbonate,
sodium carbonate,
uh, ammonium chloride.
We can add cold water bacteria,
salt-water bacteria,
any number of chemicals we can
add to get the parameters back
into the right guidelines.
>> host: Sure. Now is there
ever an instance where you
need to make a change quickly,
and you have to speed up
or slow down the rate
of reaction in a system?
>> Lea: Well, that depends
on whether that system
has animals or not.
If it's something that
doesn't have animals in it,
we can, uh-- we've had
a system that had a high pH,
so we added hydrochloric acid
to lower that.
>> host: It makes sense.
You would want to wait
'til the animals were out of
that environment before you
added the hydrochloric acid.
>> Lea: Correct, yes.
>> That could be dangerous.
Our students have just
been learning about dissolved
gasses into solutions.
What are some of the ways
that you all maintain proper
levels of dissolved gasses
in the different habitats?
>> Lea: We work closely
with our life-support team,
and they give us
a daily printout of
the current oxygen and
the current DO everyday.
They have in-line pros
that monitor the systems
24 hours a day.
>> host: And you say DO,
just for those of us who aren't
in the aquarium business...
>> Lea: That's dissolved oxygen.
>> host: Dissolved oxygen.
>> Lea: Yes.
>> host: Great. And when
you get those readouts,
how do you respond if
the numbers aren't exactly
where you want them to be.
>> Lea: If we need to increase
the dissolved oxygen
a little bit,
we may increase the oxygen
just a tad,
so the animals can relax
a little bit more.
So it-it'll cause the system
to be super saturated.
>> host: Super saturation,
we just covered that
in our previous unit,
so the students should be
familiar with that term.
>> Lea: Oh, awesome. Yay.
>> host: Now tell us a little
about your background.
Obviously you have
a lot of knowledge
of chemistry and animals
and the different habitats.
How did you end up here?
>> Lea: Actually, in high school
I had no interest at all
with chemistry.
>> host: Really!?
>> Lea: So college,
it kind of grew on me.
Um, I'm an animal science major
so I took a lot of math,
a lot of chemistry,
a lot of biology,
so it was just something
that, you know, I-I wanted
to go to vet school,
but I just wasn't committed to
doing 8 more years of school...
>> host: That's a lot of school.
>> Lea: So I saw that I had
a lot of the backgrounds
for research, so I looked
into research, and here we are.
Nine years later.
>> host: So just because
a student sitting in chemistry
right now might not think
this is their career path,
they should keep in mind
that there are options.
>> Lea: Yes, things will change.
You may have a teacher that's
amazing with explaining
the material, and you'll la--
you'll latch right onto it.
>> host: Wonderful.
That's a good thing
for everyone to remember.
>> Lea: Yes.
>> host: Thank you so much
for joining us today.
>> Lea: You're welcome.
Thanks for having me.
>> host: This unit has been
filled with new ideas
related to Reaction Rate,
as explained by
Collision Theory.
You have a good handle
on the types of factors
that can speed up
or slow down reactions,
such as temperature,
motion, and catalysts.
You also now understand
Kinetic Molecular Theory
and the Ideal Gas Law,
and how they explain
the unusual behavior of gases.
Finally, you applied
your chemistry expertise to
an engineering-design challenge,
testing your ideas for
a new environmentally
friendly airbag.
I want to once again
thank Lea Merriwhether
of the Georgia Aquarium,
for demonstrating for us
some of the real-world
applications of the concepts
we covered in this unit.
If you'd like
some additional practice
with gas law calculations,
please check out
our Closer Look video
on that topic.
It's in the Chemistry Matters
Toolkit for Unit 9.
When you're done,
I'll be waiting for you
at the top of our next
Chemistry Matters Unit,
Unit 10, Chemical Equilibrium.