5.19 Boyle's Law28 October 201111:11·5.19 use the relationship between the pressure and volume of a fixed mass of gas at constant temperature:p1V1 = p2V2
p1 = Pressure at the beginning [kPa, bar or atm]V1 = Volume at the beginning [m3or cm3]p2 = Pressure at the end [kPa, bar or atm]V2 = Volume at the end [m3 or cm3]
(Note: can use any units for V and p as long as they are the same at the beginning and end)
Monday, November 21, 2011
5.19 Boyle's Law
5.19 Boyle's Law
5.19 Boyle's Law demos02 November 201120:01
Fun with the vacuum pump!
· Marshmellows· Food colouring in pipettes· Surgicalgloves
5.19 Experiment07 November 201114:32
· Change the pressure of a fixed mass of gas at a constant temperature· Measure the volume· Use the EXCEL spreadsheet to analyse your results
5.18 Answer
5.18 Answer07 November 201115:08Collins, p.116
a. If we cool the gas in a rigid, sealed tin can, what happens to the pressure inside the can? (1 mark)The pressure will decrease
b. Explain your answer to part a. by using the Kinetic Theory (4 marks)· The volume remains the same because a tin can is a rigid container· If the temperature decreases the gas molecules have a lower average Kinetic Energy· So there are less collisions between the gas molecules and the walls of the container per second(NB: Can also say that slower molecules will collide with less force) (1 mark)
· So the pressure in the container will decrease
5.16 Virtual Experiment
5.16 Virtual Experiment28 October 201111:11·5.16 understand that the Kelvin temperature of the gas is proportional to the average kinetic energy of its molecules
1) The variable that remains constant for the experiment is the amount of the gas and the volume of the container.
2) When the temperature is increased the particles have a greater average kinetic energy therefore moving faster so they collide with the walls of the container more frequently with more force increasing the pressure.
3) no, the graph is not a straight line.
4) yes the graph of temperature against (average speed of particles)2 is a straight line.
5) the particles in a container have got a range of speed therefore a range of KEs. Some particles will be moving faster and some slower, but on average, T is proportional to KE.
5.16 Blank EXCEL template07 November 201113:51<<Ideal Gas - temperature vs average KE of particles blank table.xlsx>>
Sunday, November 20, 2011
Saturday, November 19, 2011
5.17
5.17 starter
02 November 2011 20:01 > Why do the eggs get sucked into the bottles?! Explanation· The burning paper in the bottle heats the air in the bottle
· When the egg gets placed on top, the oxygen supply in the bottle is rapidly depleted and the paper goes out
· The bottle is sealed by the egg and now has a constant volume of gas inside
· The hot gas in the bottle now starts to cool which reduces the pressure inside the bottle
· The pressure outside the bottle remains unchanged and so there is now an unbalanced force on the egg which accelerates the egg into the bottle 5.17 28 October 2011 11:11
· 5.17 describe the qualitative relationship between pressure and Kelvin temperature for a gas in a sealed container Instructions
· Launch the application on this website: http://phet.colorado.edu/en/simulation/gas-properties [cid:image001.png@01CCA5D2.01AE3110]
· Put 5 pumps of gas in
· Set volume as the Constant Parameter
· Heat to 1000K
· Watch what happens to the Pressure Conclusion
· If you increase the temperature, you increase the pressure 5.17 Demo 02 November 2011 19:56 Cloud formation
· Place a little water in the bottom of a 1½ litre plastic bottle
· Squeeze a few times
· Introduce a small amount of smoke
· Squeeze and release several times
· When you squeeze, the cloud disappears; when you release, the cloud reforms Explanation
· When the pressure increases the temperature increases and vica versa
· The "cloud" is water droplets - liquid water
· When you squeeze the bottle the temperature increases and the droplets turn into water vapour
· The smoke particles are nucleating sites on which the water can condense
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