Lab: Pressure Bottle Submitted by: Rebecca Falin Wirt County High School in Elizabeth, West Virginia
FOR THE TEACHER
Summary 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. Resource Type Lab
Grade Level High school
Objectives 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. Chemistry Topics This lesson supports students’ understanding of • Gas laws • Matter • Density Time Teacher Preparation: 10 minutes Lesson: 30-40 minutes Materials For each group: • Two 2-L bottles • One cap for bottle • One Fizz Keeper
• • •
Two aquarium thermometers Balance Ruler
Safety • 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. Teacher Notes • 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 Student Activity Sheet: Pressure Bottle
Lesson Safety • 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. Procedure 1. 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. 2. 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. 3. Find the mass of the bottle with the pump. Record the mass. 4. 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. 5. Record the new temperature after each set of pumps. 6. After 300 pumps, find and record the mass of the bottle with the pump. Results/Observations Bottle – Pumps Temperature (ºC)
Mass (g)
Observations
Control Pump Bottle pumps Pump Bottle 100 pumps Pump Bottle 200 pumps Pump Bottle 300 pumps
– no – – –
Analysis 1. Draw a representation of what the particles look like inside the bottle Particles with no pumps Particles after 300 pumps
2. What is the relationship between volume of air in the bottle (number of pumps) and the temperature of the gas?
3. 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). 4. What is the mass of air pumped into the bottle? 5. 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). 6. What is the density of the air you pumped into the bottle? Conclusion Explain the relationship between number of air particles, pressure, and temperature and why you think these relationships exist.
