Required Practical 8: Boyles Law

Question 1

Describe a method to investigate Boyle’s law

Answer 1

1) measure the inside diameter of the syringe with a vernier calliper, with the plunger removed
2) replace plunger and draw 4ml of air. Record this
3) fit the rubber tubing over the nozzle and clamp it with a pinch clip as close to the nozzle as possible
4) set up apparatus and hang a mass hanger with a 100g mass suspended
5) gently move the plunger up and down to make sure it doesn’t stick and release it
6) record the new volume on the syringe scale
7) add 2 more 100g masses and repeat. Keep adding 2 100g masses until the total mass is 1000g
8) repeat each experiment twice more and record a mean V for each m
9) calculate the cross sectional area of the syringe
10) calculate the force exerted by each mass F=mg
11) calculate the pressure exerted by this force using F/A
12) subtract this from the atmospheric pressure to obtain values of P for each V
13) plot a graph of 1/V against P and draw a line of best fit
14) straight line through the origin should be obtained. This shows pressure is inversely proportional to volume

Question 2

Explain safety aspects

Answer 2

• use a counterweight incase the stand topples over

Question 3

How could you improve the experiment

Answer 3

• the clamp should be high enough that it doesn’t distort the syringe barrel
• lubricate the syringe to prevent the plunger sticking