Lab: Charles Law
In this lab you will explore the relationship between the temperature of a gas and it’s volume.
Mathematically this relationship can be expressed as a direct relationship (as one variable increases so does
the other). Specifically the relationship (now take a breath before you read this… and read it again and
again until you get it!) can be stated like this: the volume that a gas occupies is directly proportional to the
temperature (absolute temperature… the Kelvin scale that is… no negative values or zero, (0), (yet).. ever
try dividing by zero? (that’s why we use kelvins)). The equation looks like this V/T=K for a given mass of
gas at a pressure that doesn’t change. The K in this equation represents a constant and we will often use a
form of this equation as follows; V1/T1 = V2/T2.
Materials:
Thin stem micropipette
Colored water
Laboratory Burner
Pliers or crucible tongs
Procedure:
1.
2.
3.
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6.
Fill a thin stem micropipette with colored water. Make sure the stem is about half filled (the
stem!!… the long thin part!)
Seal the end by placing it in a burner flame and just when it begins to melt squeeze the end shut
with a pliers or crucible tongs.
Fill a beaker (at least a 250 ml beaker) about 2/3 full of dihydrogen monoxide (the non-colored
variety….nnnyyuuuuuccccckkkkkk , nnnyyuuuuuccccckkkkkk is any one awake?). Heat the
beaker and it’s contents to about 80 – 85  C. Turn the burner off.
Using a rubber band (no snapping your partner.. this means you!), attach your pipette to a ruler as
shown at the lab prep table and immerse in the beaker with water.
Wait a few seconds and note and record in your data table (one that you design) the length of the
trapped air column (remember you are measuring the volume of the trapped air,,,, the trapped air
column-not the water) and the temperature of the cooling water. You should have at least five
readings approximately 10 apart.
Prepare a graph with the independent variable on the x-axis and the dependent variable on the
Y-axis.
Questions:
1.
2.
3.
What is an independent variable and what is a dependent variable (in general that is, not
specifically as relates to the temperature and volume variables of this lab)?
Does your graph show the expected relationship between the temperature and the volume of the
trapped air column?
Using the kinetic molecular theory, explain the observed behavior of gases (the trapped air
column) in this experiment.
dstreib: microscale lab – charles law