Get the Gizmo ready:
Activity B:
 On the SIMULATION pane, set T to 100 K and m
to 0 kg.
Charles’ law
Question: How does temperature affect the volume of a gas?
1. Form hypothesis: How do you think the volume of a gas will change as the temperature
rises and falls? Hypotheses will vary.
2. Collect data: Without changing the mass on the lid, record the pressure and volume of the
gas at each of the given temperatures.
Temperature
Pressure*
Volume
100 K
98.1 N/m2
0.85 m3
200 K
98.1 N/m2
1.7 m3
300 K
98.1 N/m2
2.54 m3
400 K
98.1 N/m2
3.39 m3
500 K
98.1 N/m2
4.24 m3
*This model does not include atmospheric pressure, which is 101,325 N/m2.
3. Analyze: As the temperature increases at constant pressure, what happens to the volume of
the gas? As the temperature increases, the volume of the gas also increases.
This relationship is called Charles’ law.
4. Explain: Based on the motions of the gas molecules, why do you think the volume changed
as it did when the temperature was increased?
As temperature increased, the molecules moved faster. The faster molecules push on the lid
of the container with greater force and greater frequency, causing the lid to move up. [As the
lid moves up, the frequency of collisions decreases because the enclosed gas is less dense.
So the lid moves up until the greater force of collisions is offset by having fewer collisions.]
5. Think about it: Why do you think the pressure was the same in each test?
The weight on the lid was the same in each test, so the pressure on the gas was the same.
(Activity B continued on next page)
Activity B (continued from previous page)
6. Calculate: Compare the pressure and volume values in your data table.
A. How did doubling the temperature affect the gas volume? Gas volume doubled.
B. How did tripling the temperature affect the gas volume? Gas volume tripled.
C. How did quadrupling the temperature affect the gas volume? Gas volume
quadrupled.
7. Predict: Suppose the temperature was 50 K. What will be the volume of the gas?
Predictions will vary.
8. Test: Test your prediction using the Gizmo. What is the volume of the gas? 0.42 m3
Was your prediction correct? Check student predictions.
9. Create a graph: On the GRAPH tab, select V vs. T. Set T to 50 K, and click Record to plot a
point on the graph. Plot a point every 50 degrees to create a graph showing the relationship
between temperature and volume.
When your graph is complete, click the camera icon to take a snapshot. Paste the image
into your document, and label the graph “Volume vs. Temperature.”
A. What is the shape of the graph? A straight line moving from lower left to upper right.
B. How does this graph illustrate Charles’ law?
The graph shows that, as temperature increases, the volume increases linearly.
10. Apply: Based on what you learned, what would happen to a balloon placed in the freezer?
The balloon would shrink in the freezer because it cools down.
What would happen to a balloon placed in a warm oven? (Assume it doesn’t pop.)
The balloon would expand in a warm oven because it warms up.
11. Think and discuss: Consider temperature, pressure, and volume. How does the
mathematical relationship in Boyle’s law compare to that in Charles’ law?
Answers will vary. Sample answer: “Charles’ law is a direct relationship: as temperature
increases, volume increases. Boyle’s law is an inverse relationship: as pressure increases,
volume decreases.”
Get the Gizmo ready:
Activity C:
Gay-Lussac’s law
 On the SIMULATION pane, set T to 100 K and m
to 0 kg.
Question: How does temperature affect the pressure of a gas when volume is constant?
1. Form hypothesis: If the volume of a gas is held constant, how do you think the pressure will
change as temperature increases? Hypotheses will vary.
2. Collect data: Record the volume and pressure when T = 100 K and m = 0 kg. Then, change
T to 200 K. Adjust the m slider until the volume is the same as it was when T was 100 K.
Record the volume and pressure. Then, repeat for the other temperatures.
Pressure
Temperature
Temperature
Volume
Pressure
100 K
0.85 m3
98.1 N/m2
200 K
0.85 m
3
300 K
0.85 m
3
400 K
500 K
0.981 Pa/K
196.2 N/m
2
0.981 Pa/K
294.3 N/m
2
0.981 Pa/K
0.85 m3
392.4 N/m2
0.981 Pa/K
0.85 m3
490.5 N/m2
0.981 Pa/K
3. Analyze: Divide the pressure by the temperature to fill in the last column of the table.
A. When the volume is held constant, how does the pressure change as temperature
increases? The pressure increases as the temperature increases.
B. What do you notice about the ratio between the pressure and temperature, when
volume is constant? The pressure/temperature ratio is always 0.981 Pa/K
Gay-Lussac’s law states that, at constant volume, the ratio of pressure to
temperature is constant. As temperature increases, pressure increases as well.
4. Explain: Based on the motions of the gas molecules, why do you think the pressure
changed as it did when the temperature was increased?
As temperature increases, the molecules move faster, increasing the number of collisions
and the force of collisions between the molecules and the walls of the container. This
increases the pressure on the walls of the container.
(Activity C continued on next page)
Activity C (continued from previous page)
5. Calculate: Compare the pressure and volume values in your data table.
A. At constant volume, how did doubling the temperature affect the pressure? At
constant volume, the pressure doubled when the temperature doubled.
B. How did tripling the temperature affect the pressure? Pressure tripled.
C. How did quadrupling the temperature affect the gas volume? Pressure quadrupled.
6. Create a graph: Use your data from the
previous page to create a graph of
temperature vs. pressure on the blank grid
to the right, assuming a constant volume of
0.85 m3. Draw a line or curve to connect the
points on the graph.
What is true about the line connecting the
points? The line connecting the points on
the graph is a straight line with a slope of
just less than 1. [Slope is 0.981 Pa/K]
7. Apply: Based on what you learned, what do you think would happen if you placed a sealed
container of gas into a fire? If a sealed container of gas were placed in a fire, the
temperature and pressure of the gas would increase until the container broke or exploded.
8. Challenge: Combine Boyle’s law, Charles’ law, and Gay-Lussac’s law into a single
proportional relationship between pressure (P), volume (V), and temperature (T). Use the
symbol “∝” to represent “is proportional to.”
PV ∝ T
Explain your reasoning.
Sample explanation: Charles’ law states that, at constant pressure, volume is proportional to
temperature. Gay-Lussac’s law states that, at constant volume, pressure is proportional to
temperature. Therefore, the product of pressure and volume is proportional to temperature.
This is also consistent with Boyle’s law, which states that pressure is inversely proportional
to volume when temperature is constant.