5.18 Gay-lussac's law

· 5.18 use the relationship between the pressure and Kelvin temperature of a fixed mass of gas at constant volume:

p1 / T1 = p2 / T2

p1 = Pressure at the beginning [kPa, bar or atm ]

T1 = Absolute temperature at the beginning [K]

p2 = Pressure at the end [kPa, bar or atm]

T2 = Absolute temperature at the end [K]

(Note: the units of temperature must be Kelvin, not oC! The units of pressure can be any, as long as the same at the beginning and the end)

5.18 Experiment

07 November 2011

14:32
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· Change the temperature of a fixed mass of gas at a constant volume
· Measure the pressure
· Use the EXCEL spreadsheet to analyse your results

5.18 Ideal graph and conclusion

09 November 2011

15:15
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5.18 Question

Collins, p.116

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a. If we cool the gas in a rigid, sealed tin can, what happens to the pressure inside the can? (1 mark)
b. Explain your answer to part a. by using the Kinetic Theory (4 marks)

ANSWERS:
a)

Ideal Gas - Gay Lussac's law real results.xlsx Download this file

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5.17

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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

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· 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

5.16 Virtual Experiment

5.16 Virtual Experiment

28 October 2011

11:11
· 5.16 understand that the Kelvin temperature of the gas is proportional to the average kinetic energy of its molecules
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1. volume
2. hit the walls of the container with more force and more rapidly
3. no, because the line on the graph is not straight

https://bpsmail.patana.ac.th/OWA/attachment.ashx?attach=1&id=RgAAAADGcmrXj95m...

Ideal Gas - temperature vs average KE of particles blank table.xlsx Download this file

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homework

1. is the lowest possible temp anywhere - including outer space

2. a. 292.9K
b.423K
c. 1273K
d. 27 degC
e. 377 degC
f. 727 degC

Untitled

An investigation on the variable of temperature acting upon the reaction time between hydrochloric acid and sodium thiosulphate.docx Download this file

My Write up
Many Thanks
Ollie

Answers

5.12+5.15 Answers

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http://www.lon-capa.org/~mmp/kap10/cd283.htm

Answers
1. The particles create a pressure by colliding with the walls of the container
2. If you increase the temperature the average speed of the particles increases
3. If you increase the temperature the number of collisions per second increases
4. If you increase the temperature the pressure increases

5.11 Answers

02 November 2011

17:32

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Brownian Motion Answers.ppt Download this file

5.11

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· You're looking at smoke particles in air under a microscope
· They appear to be jiggling about
· Why?

· (Don't worry if you can't work this out straight away - Albert Einstein was the bloke who eventually explained what's happening here!)

5.11

28 October 2011

11:10
· 5.11 understand the significance of Brownian motion

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Model 1
· What does the red puck represent?
· What do the metal balls represent?
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Model 3
· What do the "smoke" particles look like?
· Why are they moving?
· What do the "air" particles look like?

5.11 explained

28 October 2011

11:10

Model 1
· What does the red puck represent?
o The large, visible smoke particle
· What do the metal balls represent?
o The small, not visible air particles

Model 2
· What do the small red particles represent?
o The small, not visible air particles
· What does the large blue particle represent?
o The large, visible smoke particle
· What does the view on the left of the screen represent?
o The view through the microscope lense
· Why can‘t you see the red particles in this view?
o They are too small to see

Model 3
· What do the "smoke" particles look like?
o They are the 5 large, sand coloured particles
· Why are they moving?
o Small, fast moving air particles are colliding with the smoke particles and making them move
· What do the "air" particles look like?
o They are the numerous, small, white particles

5.11 Questions

02 November 2011

17:21
1. Draw the path of a smoke particle in air - IN PICTURE
2. Explain what is meant by Brownian Motion of smoke particles in air and how it provides evidence for air particles - Incessant motion of matter due to thermal energy.
3. What change would you expect to see in the movement of the smoke particles if the air was cooled down? Why? - Slower movement because the warmer the temperature the more movement.

brownian_motion.swf Download this file

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5.12+5.15

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Questions
· Why does the needle on the meter move when gas particles are introduced into the box?
· What does the meter measure?

Answers
· The gas particles collide with all of the walls of the container. The wall on the right moves outwards and moves the needle.
· Pressure. The gas particles colliding with the walls makes a force on the walls. The walls have a surface area so the quantity measured is pressure, p=F/A.

5.12+5.15 Questions

02 November 2011

15:55
· 5.12 recall that molecules in a gas have a random motion and that they exert a force and hence a pressure on the walls of the container
· 5.15 understand that an increase in temperature results in an increase in the speed of gas molecules
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Try the animation http://www.lon-capa.org/~mmp/kap10/cd283.htm
1. How do the particles create a pressure? - By reacting with the surroundings and colliding.
2. If you increase the temperature, how does the movement of the particles change? - They will get faster.
3. If you increase the temperature, how does the number of collisions per second change? - It will Increase.
4. If you increase the temperature, what does this do to the pressure? - Increases the pressure.

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Ideal gases - summary of terms.pptx Download this file