Charles’ Law: The Effect of Temperature on Volume
Background
According to the kinetic-molecule theory, an increase in temperature will cause the molecules of a gas
to move faster, exert more pressure, and cause the gas particles to move farther apart. Conversely, as a
gas is cooled, the molecules will move more slowly, exert less pressure, and take up less space. In
other words, the volume of a gas increases as temperature increases if the pressure remains constant.
This relationship the volume of a gas and its temperature is known as Charles’ Law. In this
experiment, you will study the effects of temperature on gas volume and use the following equation.
V1 = V2
T1 T2
Objective
Determine the effect of temperature on the volume of a gas when
pressure is constant.
Equipment
125 mL Erlenmeyer flask
600 mL beaker
No. 5 one-hole rubber stopper with glass tubing
Graduated cylinder (50 or 100 mL) Large tub or bucket
Hot plate
Ring Stand
Buret clamp
Procedure
1. Prepare a data table as shown below. Record the atmospheric pressure using a barometer.
2. Totally fill the 125 mL Erlenmeyer flask with tap water and fit with a rubber stopper. Remove
the stopper and measure the remaining volume of water in a graduated cylinder and record it as
the total volume of the flask (V1). This will be the same for all three trials! Pour out all of the
water in the flask.
3. Set up the apparatus as shown in Figure 1. Obtain a 600 mL beaker and add approximately 250
mL of tap water. Obtain a 125 mL Erlenmeyer flask. Place a one-hole stopper fitted with a 3
cm glass tube in the flask and place the flask in the beaker as shown in Figure 1. Be sure to tilt
the flask at an angle so that bubbles can escape off the side when the water in the beaker boils.
4. Heat the water in the beaker to a low boil. Lower the setting on the hotplate to around 5-6 once
boiling has been achieved. Record this temperature as T1 in your data table. Convert ºC to K.
Continue heating at this temperature for 3 to 5 minutes.
NOTE: By keeping the Erlenmeyer flask in the boiling water for a few minutes, you can
assume that the air in the flask is the same temperature as the boiling water – This is T1 for
the gas!
5. Add water to the tub or bucket if it has not already been done for you.
6. Carefully place your finger firmly over the end of the glass tubing in the stopper of the
Erlenmeyer flask. Keep the opening covered until step #8! Remove the flask from the beaker.
Protect your hand with a towel and use group work! CAUTION: Flask is hot!
7. Invert and submerge the flask in the tub as shown in Figure 2. Do not allow air to enter the
flask while transferring!
8. Remove your finger from the glass tubing and hold the flask under water (glass tube down)
until the flask has cooled and the water ceases to enter. This will take a few minutes. The flask
should no longer feel warm to the touch.
NOTE: By keeping the Erlenmeyer flask in the tub water, you can assume that the air in
the flask is the same temperature as the water in the tub – this is T2 for the gas! You will
record this in step #9.
9. Raise the flask (glass tube down), until the water level inside is equal to the water level outside
as in Figure 2. The pressure inside the flask is now equal to the atmospheric pressure. This is
important because otherwise pressure would not be constant.
10. Place your finger over the glass tubing when the
outside and inside water levels are equal. Remove the
flask and place it in an upright position on your lab
table before removing your finger. Measure the
temperature of the water in the flask and record as T2.
11. Measure the volume of the water in the flask with a
graduated cylinder. Record the volume of water in the
flask in your data table.
12. Subtract the volume of water in the flask from the
total volume of the flask to find the final volume of
gas (V2).
13. Repeat this procedure using different temperatures: Trial 2 (50-60ºC) and Trial 3 (4-12ºC)
Data
A) Prepare a data table as shown below to record your experimental data. Use the following
conversations to record temperature in Kelvin and pressure in kilopascals.
K= ºC+273
101.3 kPa=760 mm Hg
Pressure in the room: ____________ mmHg = ______________ kPa
Variable What is it…
Trial 1
Trial 2
V1
Total volume of the flask
T1
Temp of boiling water =
_____ ºC
_____ ºC
temp of air in flask
_____ K
_____ K
Volume of water in flask
V2
= (Total volume of flask –
volume of water in flask)
T2
Temperature of water in
_____ ºC
_____ ºC
flask
_____ K
_____ K
Trial 3
_____ ºC
_____ K
xxxxx
_____ ºC
_____ K
Conclusion
1. Use Charles’ Law to calculate the V2 for Trial 3. Show your work! Record your answer in the
data table.
2. Graph your data by plotting temperature in Kelvin on the horizontal axis and volume in
milliliters on the vertical axis for each trial. You will have three lines on the graph. Each line
will consist of two points (T1, V1) and (T2, V2). Be sure to make a key, a title and labeled axes.
3. Look at your graph of temperature vs. volume. In your own words, explain the relationship that
exists between the variables.
4. Calculate the theoretical V2 for trials one and two (You already have V1, T1, and T2). Show
your work!
5. What are some explanations for the error seen between the theoretical V2 values and your
experimental V2 values in this lab?
6. How would your data be affected if you did not equalize the pressure in Step 5?
7. Water did not enter the flask in all trials. Explain this using Charles’ Law.