Name: Teacher: Class: Investigation of Boyle s Law: methods Your task is to investigate the relationship between volume, pressure and temperature for a gas. You must write detailed methods and select appropriate equipment and materials. Please include diagrams of the experimental setup. You must justify your choices with reference to experimental error and safety. Please give references for all your sources of research. Available equipment includes: Syringe (1ml, 10ml, Thin walled rubber 100ml, 1000ml) or silicone tubing Masses (10g, 20g, glass capillary 50g, 100g, 0.5kg, 1 tubing kg, 2kg) Sulphuric acid Rule (30cm, 50cm, Thermometer 1m) Kettle Beaker (10ml, Pinch clip 100ml, 150ml, Loop of string 500ml, 1l, 2l, 5l) Elastic bands Micrometer Stand and clamps G-clamp Paper towels Bunsen burner Manometer Tripod and gauze Foot pump Coloured oil Please use the following headings in your work, you may need to use your own subheadings: Equipment and materials Diagram Method References You may complete this task on a computer or by hand, work must be clear and legible, and a physical copy must be presented to your teacher.
Boyle s law : method 1 syringe & retort stand Materials and equipment Stand and clamp 10ml syringe with 0.5ml divisions 5cm length of thin-walled rubber or silicone tubing to fit nozzle of syringe Pinch clip 2kg mass Loop of string 9 x 100g masses on a 100g mass holder Micrometer Diagram Method 1. Remove the plunger from the syringe and measure the diameter of the rubber seal, d, using the micrometer. Convert this into metres. 2. Calculate the cross-sectional area of the seal A = πd2/4 in m2. 3. Replace the plunger and draw in 4.0ml of air. 4. Fit the rubber tubing over the nozzle, fold the tubing over and clamp it with the pinch clip as close to the nozzle as possible.
A2 Physics Practical : Boyle s Law and Charles s Law: sheet 2 Page 3 5. Set up the apparatus as shown in the diagram initially with the 100g mass holder carrying one 100g mass. Ensure that the string is securely attached to the plunger handle. The clamp should be above the plunger so that the scale can be read. Clamping the syringe barrel can distort it, making it more difficult for the plunger to move freely. Consequently, ensure the clamp is high enough on the barrel above the position where the plunger moves. There should be sufficient room below the masses so that the plunger can move down as masses are added. 6. Gently move the plunger up and down a few millimetres to ensure it is not sticking. 7. Read the new volume on the syringe scale (fractions of a division should be estimated). 8. Repeat the procedure with an extra two 100g masses added to the holder each time, up to a total mass of 1000g. 9. The whole experiment should then be repeated to obtain a second set of results, and the mean volumes found. 10. The force exerted by the masses can be calculated using F = mg where m is the mass in kg and g, the gravitational field strength, is 9.81Nkg-1. 11. The pressure exerted by this force on the air sample is then F/A in Pascals (Pa). Convert this into kpa. 12. This should be subtracted from standard atmospheric pressure, 101kPa, to obtain the pressure of the air sample, P. (Note: the initial volume of the air with no masses hung on the loop will be at standard atmospheric pressure). 13. A graph of 1/V against P should then be plotted (where V is the mean volume of the air sample for each value of P). 14. Provided care has been taken to ensure the plunger does not stick, a reasonable straight line through the origin should be obtained. (Any slight sticking could result in a graph which curves slightly and/or does not pass through the origin.) You will need to create a table for your measurements and calculations which you will use to draw your graph. References AQA (2016) Practical handbook for A level physics, v1.3, [online] Last accessed on 1 st September 2016. http://filestore.aqa.org.uk/resources/physics/aqa-7407-7408-phbk.pdf
A2 Physics Practical : Boyle s Law and Charles s Law: sheet 2 Page 4 Boyle s law : method 2 Boyle s Law apparatus Materials and equipment Boyle s law apparatus manometer tube, oil reservoir, Bourdon gauge and valve foot pump Vernier calipers Diagram Method 1. Set up apparatus as shown in the diagram. 2. Connect air pump to the inlet valve of the oil reservoir. 3. Note the manometer reading for the gas column length at atmospheric pressure. 4. Measure the internal diameter of the manometer tube using Vernier calipers for volume calculations.
A2 Physics Practical : Boyle s Law and Charles s Law: sheet 2 Page 5 5. Open air tap and pump in air until the manometer reads a gas column length of no less than 10 cm. 6. Quickly close inlet valve. 7. Leave the apparatus for a minute. After compressing the air in a short period, the temperature will have risen. This time is required to allow the temperature to fall back to room temperature. 8. Read & record the gas pressure by reading it off the Bourdon gauge. Using pressure as the independent variable: use the initial pressure to determine the approximate pressure interval required to give at least six regularly spaced data points on the graph (see below). This will give evenly spaced points on the graph. Using the initial volume to determine the approximate volume interval to give six data 9. Read & record the gas column length from the manometer scale. Using volume as the independent variable: use the initial gas column length (above) and unpressurised gas column length (step 3) to find the maximum and minimum values of (1/V). Find the interval of (1/V) required for six regularly spaced data points and determine the approximate values of 1/V and hence V to be used during the experiment. This will give evenly spaced points on the graph. 10. Gently release from air from the reservoir by opening the inlet valve slightly then closing once the pressure has fallen by the interval calculated in Step 7. 11. Leave the apparatus for a minute to come back into thermal equilibrium with the room. 12. Read & record the gas pressure by reading it off the Bourdon gauge. 13. Read & record the gas column length from the manometer scale. 14. Repeat steps 9-12 until the pressure of the gas is back to atmospheric pressure. 15. Repeat the above procedure at least one more time to reduce random uncertainties in the values obtained. 16. Calculate mean values of the pressure and/or volume. 17. Plot a graph of pressure (p) against the inverse of volume (1/V). References Muncaster, R. (1991) A-level physics, 3 rd ed., Cheltenham, Stanley Thornes.