Required Practical 8

Boyle's Law - Equipment

Stand and clamp Syringe  Rubber tubing  Pinch clip String 100g masses with 100g holder

Boyle's law - Method

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

Required+Practical+8+(1) (binary/octet-stream)

Boyle's law - graphs and calculations

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.

Boyle's law - Safety

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

Boyle's law - Improvements and notes

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

Charles' law - Equipment

Capillary tube Sulfuric acid  2 litre beaker  2 elastic bands 30cm ruler Thermometer Kettle

Charles' law - Method

Set up the apparatus as shown in the diagram with the open end of the capillary tube at the top and add hot water from the kettle. The hot water should cover the air sample Stir the water well using the thermometer and read and record the value of its temperature, θ, and the length of the air sample, l, on the 30cm ruler. Allow the water to cool by 5°C and repeat this, taking measurements every 5°C down to room temperature

Required+Practical+8(2) (binary/octet-stream)

Charles' law - Graphs and calculations

Plot a graph of l against θ, draw a line of best fir, and find the gradient m. The value of absolute zero can be found by θ(0) = θ(1) =l(1)/m, where θ(1) and l(1)are pair values on the lines of best fit l(1)=mθ(1)+c ⇒ c = l(1) -mθ(1) At absolute zero, l=o so θ(0) = θ(1)-l(1)/m

Charles' law - safety

Safety googles must be worn because concentrated sulfuric acid can cause damage to the eyes  Boiling water is being used which could cause burns, so care must be taken it does not spill

Charles' law - Improvements and notes

The tube needs to be perfectly clean with no traces of other chemicals to prevent the thread of sulfuric acid from splitting