Investigation of Boyle’s (constant temperature) law

Question 1

Equipment

Answer 1

○ Stand and clamp

○ Syringe

○ Rubber tubing

○ Pinch clip

○ String

○ 100g masses with 100g holder

Question 2

Method

Answer 2

○ With the plunger removed from the syringe, measure the inside diameter d of the syringe using a vernier caliper.

○ Replace the plunger and draw in about 4.0ml of air and record this. Fit the rubber tubing over the nozzle and clamp it with the pinch clip as close to the nozzle as possible.

○ Set up the apparatus as shown in the diagram, with only the 100g holder and one 100g mass suspended.

○ Gently move the plunger up and down to ensure it is not sticking and release it. Record the new volume V on the syringe scale.

○ Add two 100g masses to the holder and repeat this, adding two 100g masses each time until the total mass is 1000g.

○ Repeat the experiment twice more and find and record the mean V for each m.

Question 3

Graphs and calculations

Answer 3

○ Calculate the cross sectional area A of the syringe using A = πd^2/4

○ Calculate and tabulate the force F exerted by each mass m using F=mg.

○ Find the pressure exerted by this force using F/A. Subtract this from standard atmospheric pressure, 101kPa, to obtain the pressure P of the air sample at each V.

○ Plot a graph of 1/V against P and draw a line of best fit. A straight line through the origin should be obtained, showing that the pressure is inversely proportional to the volume.

Question 4

Safety

Answer 4

○ The stand could topple over and cause injury so a counterweight can be used if it is deemed unstable.

Question 5

Improvements and notes

Answer 5

○ The clamp should be high enough that it does not distort the syringe barrel and make it more difficult for the plunger to move freely.

○ The syringe can be lubricated to prevent the plunger from sticking.