In this lab, students determine the relationship between volume and pressure of a gas and its temperature. This lab also addresses the misconception that air does not have mass or density by having students determine the mass and density of air pumped into a bottle.
By the end of this lesson, students should be able to understand:
- that air has mass and density
- the relationship of pressure and temperature for gases
This lesson supports students’ understanding of
- Gas laws
Teacher Preparation: 10 minutes
Lesson: 30–40 minutes
- Two 2-L bottles
- One cap for bottle
- One Fizz Keeper
- Two aquarium thermometers
- When you are done, call the teacher over to release the pressure on the bottle—DO NOT DO IT YOURSELF.
- Always wear safety goggles when working in a chemistry lab.
Flinn includes a lab using the Fizz Keeper to show the relationship between temperature and volume (or pressure) of a gas. I find that my students often think that air has no mass and no density, so I adapted this lab to address that misconception.
For the Student
- Obtain two 2-L bottles, each having an aquarium thermometer attached to the side. One bottle has a cap on it and will serve as the control. The second bottle will contain a Fizz-Keeper pump on the top.
- Read the temperature by locating the value that has a light green highlight on it. Record the temperature on the control bottle and pump bottle.
- Find the mass of the bottle with the pump. Record the mass.
- Add the specified number of pumps of air into the pressure bottle. Add air pumps at a regular rate—do not add them too quickly.
- Record the new temperature after each set of pumps.
- After 300 pumps, find and record the mass of the bottle with the pump.
Results & Observations
|Bottle Pumps||Temperature (degrees Celsius)||Mass (g)||Observations|
|Pump Bottle (no pumps)|
|Pump Bottle (100 Pumps)|
|Pump Bottle (200 Pumps)|
|Pumps Bottle (300 Pumps)|
- Draw a representation of what the particles look like inside the bottle.
- What is the relationship between volume of air in the bottle (number of pumps) and the temperature of the gas?
- Create a line graph to show the relationship between the temperature of the air and the volume of air in the bottle (number of pumps).
- What is the mass of air pumped into the bottle?
- Determine the volume of each pump of air:
- What is the diameter of the shaft of the pump?
- What is the length of the shaft of the pump?
- Using the formula for the volume of a cylinder, estimate the volume of the shaft of the pump (and thus the volume of one pump of air).
- What is the density of the air you pumped into the bottle?
Explain the relationship between number of air particles, pressure, and temperature and why you think these relationships exist.