In this activity, students will use an animation to visualize how the quantity, volume, temperature, and pressure of a gas are related. This is done qualitatively through the balloon and bell jar scenarios. Quantitative relationships, with the corresponding laws, are summarized at the end.
Middle School, High School
This activity will help prepare your students to meet the performance expectations in the following standards:
- Scientific and Engineering Practices:
- Developing and Using Models
By the end of this activity, students should be able to:
- Describe the relationships between the quantity, volume, temperature, and pressure of a gas.
This activity supports students’ understanding of:
- Gas laws
Teacher Preparation: minimal
Lesson: 10-30 minutes
- Computer and projector with internet access
- Student handout
- No specific safety precautions need to be observed for this activity.
- All of the animations that make up the AACT Animation collection are designed for teachers to incorporate into their classroom lessons. Intentionally, these animations do not have any spoken explanations so that a teacher can speak while the animation is playing and stop the animation as needed to instruct.
- We suggest that a teacher pause this animation at several points or watch it more than once to give students the opportunity to make notes, ask questions, and test their understanding of the concepts presented. The animation is a little over 1 minute long and moves quickly, so students will likely require pausing or multiple viewings to successfully complete the student activity sheet if you choose to use it.
- If you assign this to students outside of class time, you can create a Student Pass that will allow students to view the animation (or any other video or ChemMatters article on the AACT website).
- This animation provides qualitative examples of the relationships between the four commonly compared gas variables: quantity (n), volume (V), temperature (T), and pressure (P). Particle diagrams are shown for pairs of variables depicting how changing one variable affects the other, including the direct relationships between quantity and volume, temperature and volume, temperature and pressure, and the inverse relationship between pressure and volume.
- In this animation, a balloon is used to represent systems with variable volume, and a bell jar is used for systems with variable pressure.
- You can use this animation to visually demonstrate the definitions of temperature – a measure of the average kinetic energy of particles (how fast the particles in the balloon or bell jar are moving) – and pressure – a measure of force per unit area (how often/how hard the particles collide with the walls of the balloon or bell jar).
- Air (nitrogen and oxygen) and helium are used as example gases throughout this animation. It might be interesting to have a discussion with students about whether the type of gas effects the properties and relationships shown in the animation. (The type of gas won’t play a role in most gas laws calculations until you get to the AP/college level and start working with real/non-ideal gases. This could be a place to discuss the assumptions made by the treatment of gases as “ideal gases.”)
- Throughout the animation, qualitative comparisons are made between select variables. At the end of the animation, four equations for the four different gas laws shown in this animation are displayed, but students are not asked to do any calculations. There are numerous AACT resources (including a Gas Laws Unit Plan) that can be used to teach gas laws quantitatively in greater depth, some of which are listed below.
- The final question before the extension section asks students to describe the relationships between variables that they saw in the animation as direct or inverse relationships. If your students aren’t familiar with these terms it may help to define them before they answer this question. (Direct relationships occur when an increase in one variable causes an increase in the other, and inverse relationships occur when an increase in one variable causes a decrease in the other.)
- Related classroom resources from the AACT Classroom Resource Library that may be used to further teach this topic:
For the Student
As you view the animation, answer the questions below.
- What types of gas particles are initially present in the balloon? What type of gas particles are added to fill the balloon?
- Based on what happens to the balloon when more gas is added, what is the relationship between the quantity of gas particles (n) and the volume (V) of a gas?
- What happens to the way the gas particles move when the balloon is taken outside? What does this indicate about the temperature of the gas?
- Based on what happens to the balloon when it is taken outside, what is the relationship between the temperature (T) and volume (V) of a gas?
- Circle the bolded phrase that best completes the sentence: When the balloon is first placed in the bell jar, the number of collisions of gas particles on the outside of the balloon is ( much higher than / much lower than / about the same as ) the number of collisions of gas particles on the inside of the balloon.
- Circle the bolded phrase that best completes the sentence: When the vacuum is turned on, the number of collisions of gas particles on the outside of the balloon is ( much higher than / much lower than / about the same as ) the number of collisions of gas particles on the inside of the balloon.
- Based on what happens to the balloon in the bell jar when the vacuum is turned on, what is the relationship between the pressure (P) and volume (V) of a gas?
- Based on what happens to the gas in the bell jar when it is taken outside and heated up, what is the relationship between the temperature (T) and pressure (P) of a gas?
- Summarize: For each of the four pairs of variables presented in this animation, identify them as directly or inversely related by circling the correct description:
|a. Quantity (n) and Volume (V):||Direct||Inverse|
|b. Temperature (T) and Volume (V):||Direct||Inverse|
|c. Pressure (P) and Volume (V):||Direct||Inverse|
|d. Temperature (T) and Pressure (P):||Direct||Inverse|
- Choose one of the pairs of variables you saw in the animation and research a practical, real-life application or phenomenon that demonstrates the relationship between those variables. Describe how that relationship contributes to the application or phenomenon. Cite the sources you referenced.