Boyle's Law

Introduction

Gases are compressible. The quantitative relationship between pressure and volume was studied by Robert Boyle. In this experiment, you will try to discover a relationship between the volume and pressure of a sample of gas trapped in a closed hypodermic syringe.

Go to Top

1. In the center of one cardboard square make a hole large enough to accommodate the barrel of the syringe.
2. Secure one ring on the support stand at a convenient viewing height. Move the piston in the syringe to the 1mL (0.5 mL for the smaller size) setting. Carefully place the syringe through the small hole in one cardboard square. Remove the needle protector and insert the needle into the soft rubber stopper (or some modeling clay). Set this assembly on the center of the lower ring. Place the second ring about 10 cm above the first ring.
3. In the center of the second cardboard square cut a hole large enough for the beverage can to move up and down freely but not flop from side to side. See the following figure.
4. Find the mass of the topless empty beverage can. Add enough water to the can to make the mass of the can plus the water equal to 50 g. Place the remaining cardboard square on the top ring and pass the can through the hole and rest the center of the can on the top of the piston.
5. Press down on the can to force the plunger of the syringe down and then release.
6. Record the mass of the can and the water; record the volume of the syringe. (Do not use the data point for 0 mass and either 0.5 mL or 1.0 mL.)
7. Add water to the can in 50 mL increments. Record the mass and the volume each time. Continue the procedure until the total mass is 350 grams.
8. Disassemble the equipment carefully according to the instructor's instructions. Make two graphs of the data. On the first, graph the volume on the x-axis and pressure (mass) on the y-axis. On the second graph, plot 1/volume on the x-axis and the pressure (mass) on the y-axis.

Go to Top

Wear safety goggles and aprons in the lab at all times. Exercise extreme caution in dealing with the needles on the insulin syringes -- they are very sharp and can cause injury. Keep needles covered with clay or soft stopper at all times. Topless soda cans can cause cuts; be careful in handling them.

Go to Top

Go to Top

• Be careful removing the top from the aluminum beverage can. A standard can opener will not work since the top sets well below the rim of the can. The top can be removed by carefully cutting around the inside rim with a sharp heavy duty cutting knife. You may want to put tape around the sharp lip which remains inside the can. The depression at the bottom of the can helps keep the force centered over the plunger.
• Removing most of the needles with metal snippers is possible if clay is used as the closing mechanism. This will minimize the chance of a puncture injury resulting from an accidental stabbing with the needle.
• Avoid spilling water on the top cardboard support; the wet cardboard expands and causes friction.
• Although mass is plotted, the actual units should be units of pressure. Pressure is force divided by area. Force (due to gravity) is given by mass times acceleration due to gravity.
  

Go to Top

• 1 0.5mL or 1-mL Insulin syringe
• 1 soft rubber stopper
• 1 354-mL aluminum beverage can with top removed
• 1 support stand
• 2 medium rings for support stand
• 2 cardboard squares, larger than the rings
• 1 50-mL graduated cylinder
• 1 triple beam balance
  

Go to Top

The microscale version of this lesson was developed by:

Jared Ketner
Wahoo High School
Wahoo, Nebraska

Go to Top