Student Exploration: Boyle’s Law and Charles’s Law GIZMO (ALL ANSWERS ARE 100% CORRECT)

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Name: Date:

Student Exploration: Boyle’s Law and Charles’s Law

Vocabulary: absolute zero, Boyle’s law, Charles’s law, Gay-Lussac’s law, Kelvin scale, pressure

Prior Knowledge Question (Do this BEFORE using the Gizmo.)

A small helium tank measures about two feet (60 cm) high. Yet it can fill over 50 balloons! How

can such a small tank contain enough helium to fill so many balloons?

The gas in the tank is under a lot of pressure, so a lot of gas can be fit in the tank.

Gizmo Warm-up

The Boyle’s Law and Charles’s Law Gizmo shows a container

of gas. Inside, small purple spheres represent gas molecules.

1. Observe the particles. Are they all moving at the same

speed? No, the speeds are different

2. How do the particles interact with the walls and lid of the container? The bounce off of the

walls and the lid

These interactions contribute to the pressure on the walls of the container. Pressure is

defined as force per unit area. The SI units of pressure are newtons per square meter

(N/m2

), or pascals (Pa).

3. Slowly drag the temperature (T) slider back and forth. (Note: In this Gizmo, the Kelvin scale

is used to measure temperature. On the Kelvin scale, 0 degrees is absolute zero, the

coldest possible temperature. Absolute zero is equal to -273.15 °C or -459.67 °F)

A. How does the change in temperature affect the speed of the molecules? The

molecules move faster

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B. How does the change in temperature affect the volume of the container?

Volume increases

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Question: How does pressure affect the volume of a gas?

1. Form hypothesis: In this experiment, you will pile weights on the lid of the container of gas.

What do you think will happen as more weight is added to the lid?

Volume will decrease

2. Notice: Look at the DESCRIPTION pane. What is the mass of the lid? 10kg

How much pressure does the lid exert on the gas? 98.1

3. Collect data: With the temperature held constant at 300 K, use the Select mass slider to

place weights on the lid. Record the pressure and volume of the gas for each added mass.

Added mass

on the lid

Total mass

(lid + added mass) Pressure* Volume

0 kg 10 kg 98.1 N/m^2 2.54 m^3

10 kg 20 kg 196.2 N/m^2 1.27 m^3

20 kg 30 kg 294.3 N/m^2 0.85 m^3

30 kg 40 kg 392.4 N/m^2 0.64 m^3

*This model does not include atmospheric pressure, which is 101,325 N/m2

.

4. Analyze: As the pressure increases at constant temperature, what happens to the volume of

the gas? As pressure increases, gas volume decreases

This relationship is called Boyle’s law.

5. Calculate: Compare the pressure and volume values in your data table.

A. How did doubling the pressure change the gas volume? Divided by 2

B. How did tripling the pressure change the gas volume? Divided by 3

Get the Gizmo ready:

Set the temperature (T) to 300 K.

Check that the mass (m) is set to 0 kg.

Activity A:

Boyle’s law

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C. How did quadrupling the pressure change the gas volume? Divided by 4

(Activity A continued on next page)

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Activity A (continued from previous page)

6. Predict: If the added mass on the lid was 50 kg, a total mass of 60 kg would exert pressure

on the gas inside the container. What will be the volume of the gas? 42

7. Test: Test your prediction using the Gizmo. What is the volume of the gas? 42

Was your prediction correct? yes

8. Create a graph: On the GRAPH tab, select V vs. P. Set m to 0 kg, and click Record to plot

a point on the graph. Plot a point for each possible mass to create a graph showing the

relationship between pressure and volume.

When your graph is completed, click the camera ( ) icon to take a snapshot. Right-click

the image, and click Copy Image. Paste the image into a blank word-processing document,

and label the graph “Volume vs. Pressure.”

A. What is the shape of the graph? A downwards curve from left to right

B. How does this graph illustrate Boyle’s law? Pressure increases, gas volume

ddecreases

C. How do you think the graph might change if the temperature was held constant at a

higher temperature, say 400 K? The pressure would stay the same

9. Apply: Think about a small helium tank that can fill 50 balloons. What must be true about the

helium in the tank compared to the helium in the balloons?

The helium in the tank must be under higher pressure than the balloon

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Activity B:

Charles’s law

Get the Gizmo ready:

• On the SIMULATION pane, set T to 100 K and m

to 0 kg.

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? Rises

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 .85

200 K 98.1 1.7

300 K 98.1 2.54

400 K 98.1 3.39

500 K 98.1 424

*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? It increases

This relationship is called Charles’s 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 the temperature increased, the

molecules increased in speed

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5. Think about it: Why do you think the pressure was the same in each test? Weight

on the lid was the same

(Activity B continued on next page)

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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? 42

8. Test: Test your prediction using the Gizmo. What is the volume of the gas? 42

Was your prediction correct? yes

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 diagonal line from lower

left than upper right

B. How does this graph illustrate Charles’s law? As temp increases, volume

increases linearly

10. Apply: Based on what you learned, what would happen to a balloon placed in the freezer?

It would shrink, because it cools down

What would happen to a balloon placed in a warm oven? (Assume it doesn’t pop.) It

would expands because it warms up.

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11. Think and discuss: Consider temperature, pressure, and volume. How does the

mathematical relationship in Boyle’s law compare to that in Charles’s law?

Charles law is a direct relationship, Boyle’s law is an inverse relationship.

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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? Decreases

2. Collect data: Select the TABLE tab. Record the pressure when T = 100 K, 200 K, and so

forth up to 500 K. (Note: The volume will remain constant at 1.02 m3

.)

Temperature Pressure Pressure

Temperature

100 K 98.1 .981

200 K 196.2 .981

300 K 294.3 .981

400 K 392.4 .981

500 K 490.5 .981

3. Analyze: Divide the pressure by the temperature to fill in the last column of the table. Since

1 N/m2

is equal to 1 pascal (Pa), write the units of the ratio as Pa/K.

A. When the volume is held constant, how does the pressure change as temperature

increases? Pressure increases as temperature increases

B. What do you notice about the ratio of pressure to temperature, when volume is

constant? It is always .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.

Get the Gizmo ready:

On the SIMULATION pane, set T to 300 K and m

to 15 kg.

Turn on the Constant volume checkbox.

Activity C:

Gay-Lussac’s Law

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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? Temp increases the molecule

speec increases, which increases collisions.

(Activity C continued on next page)

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Activity C (continued from previous page)

5. Calculate: Compare the pressure and temperature values in your data table.

A. At constant volume, how did doubling the temperature affect the pressure?

Pressure doubled when temperature doubles

B. How did tripling the temperature affect the pressure? Tripled

C. How did quadrupling the temperature affect the gas pressure? Quadrupled

1. Create a graph: Record the pressure for temperatures of 50 K, 150 K, 250 K, 350 K, and

450 K. On the GRAPH tab, select P vs. T. Click the camera icon to take a snapshot. Paste

the image into your document, and label the graph “Pressure vs. Temperature.”

A. What is the shape of the graph? Straight line

B. How does this graph illustrate Gay-Lussac’s law? Direct relationship between

temp and volume

6. Apply: Based on what you learned, what do you think would happen if you placed a sealed

container of gas into a fire? Th temp and pressure would both increase

7. Challenge: Combine Boyle’s law, Charles’s 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

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Explain your reasoning. Charles law says constant pressure=vol is proportional to

temperature. Gay lussac’s law states at constant volume pressure is proportional to

temperature.

student exploration: boyle’s law and charles’s law gizmo

student exploration boyle's law and charles law quizlet