>> host: Welcome back to
"Chemistry Matters."
We've been preparing to conduct
a calorimetry experiment
so we can make our very own
hot and cold packs.
By now, you've created
an experimental procedure
so you can perform this lab
just like our students.
So now we'll go back
to our classroom
to see the procedures
our students have written,
and you can compare them
to your own.
>> professor: Let's review
your experimental procedures
before we get started.
Who wants to go first?
>> student: We will.
I think we're ready.
>> professor: All right.
I'll put your procedure up
and then you can
tell us about it.
>> student: Well,
we started with safety.
Then we said to put plain
water in each of the beakers
and measure the temperature
of just the water.
>> professor: Okay.
Did you use tap water
or distilled water?
>> student: We hadn't
really thought about it.
Does it matter?
>> professor: It's actually
important to use
the distilled water,
because tap water has several
additives in it that might
interfere with your results.
Do you plan to add all of
the ionic compounds to the
beakers at the same time?
>> student: Well, I guess
we'll add them one at a time
to make sure we get
the most accurate result.
>> professor: Good.
And as you saw with the
hot packs and the cold packs,
the reaction happens
very quickly.
So it's a good idea to take
the temperature often.
And your suggestion of
taking the temperature
every 10 seconds,
I think that will work as well.
And I also like the layout
of your data table here.
It's important to be prepared
to record your data before
you start an experiment.
So I'd say the two of you
are ready to begin.
But before you do,
let's take a look at
the other team's procedure.
Maria, would you like to
give us an overview?
>> student: Yeah.
Well, we made a list
of materials first,
so it would be easier
to get organized.
>> professor: I see that.
Good idea.
>> student: And we thought
the amount of distilled water
should be accurate,
so we decided to use
a graduated cylinder.
>> professor: You're right,
Maria.
The temperature change
depends directly on
the quantity of water,
so it's important to measure
the amount of water precisely.
Team one, you should use
a graduated cylinder as well.
>> student: We forgot to
make a data table though.
But we wrote out
our procedure.
>> professor: Okay, well,
you can make a data table now,
and then I think both teams
will be ready to
start the experiment.
When you're done,
analyze your data
and get prepared to
give us your conclusions
about which ionic compound is
most suitable for a hot pack
and which one is most suitable
for a cold pack.
>> student: Okay, we need to
weigh 5 grams of
calcium chloride.
I'll measure it out
with the scoopula and use
the electronic balance.
>> student: Don't forget
to zero it first.
>> student: I'll attach
the thermometer to the
ring stand for measuring
the water inside
the calorimeter.
>> student: All right,
I already put the water
in the calorimeter.
>> student: Looks like
we're ready.
Let's add the 5 grams of
potassium chloride to the
water in our calorimeter.
>> student: Great.
And I'll tighten the lid
as quickly as I can
for accuracy.
Can you hold that for me?
>> student: I'll call
the time every 10 seconds
and you write it down.
>> student: Let's get the
starting temperature first.
>> student: 20 seconds.
>> student: 25.2.
>> student: 30 seconds.
>> student: 26.4.
>> host: Analyzing your data
and drawing conclusions
based on your data
is just as important
as conducting the experiment.
It's important to organize
your data in a way that
will allow you and others
to observe trends
and patterns.
You may choose to present
your data in your
original data table,
or you may decide that
a graphical presentation
is more informative.
Regardless of how you organize
and present your data,
you'll need to draw
a conclusion based on
your data that addresses
the original experimental goal,
which is to design an effective
hot pack and cold pack.
Be prepared to justify
your conclusion,
again, using your data.
Good luck,
and I'll see you back here
when you've had a chance to
not only complete this lab,
but also to analyze your data
and draw conclusions.