5.18 Gay-lussac's law

 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 Ideal graph and conclusion

09 November 2011

15:15

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5.18

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 smoke particles are nucleating sites on which the water can condense

 

 

 

5.18 Gay-lussac's law

28 October 2011

11:11

·         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 Ideal graph and conclusion

09 November 2011

15:15

 

 

5.18 Question

07 November 2011

15:08

Collins, p.116

a.If we cool the gas in a rigid, sealed tin can, what happens to the pressure inside the can? (1 mark)

P1/T1 = P2/T2  

20+273= 293=    55+273=328

3/293 = P2/328

P2= (3 x 328) / 293 = 3.36 Bar

b.               Explain your answer to part a. by using the Kinetic Theory (4 marks)

When the temperature decrease, the kinetic energy decrease making the particles moving slower and colliding less, hitting the walls less frequently  therefore have less pressure.  

5.17

02 November 2011

20:01

	<<Video - Egg sucked into a bottle by Guy-Lussac's Law.flv>>

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

·         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

Video - Egg sucked into a bottle by Guy-Lussac's Law.flv Watch on Posterous

5.16

5.16.docx Download this file

5.14

5.14 describe the Kelvin scale of temperature and be able to convert between the Kelvin and Celsius scales

Converting Centigrade to Kelvin
T_K = T_oC + 273

Converting Kelvin to Centigrade
T_oC = T_K – 273

T_K = Temperature in Kelvin [K]

T_oC = Temperature in Degrees Centigrade [^oC]

 

 

5.14 Questions

02 November 2011

18:29

·         Collins p.118

Q1. Absolute zero is when the air particles are stop moving where they have 0 kinetic energy.

Q2. A) TK = Toc + 273

i)293K     ii) 423K   iii) 1273K

B) Toc = Tk – 273

i) 27c  e)377c           iii) 727c

PhET Gas Properties simulation

Click to Run

5.13

5.13 Starter

02 November 2011

18:17

·         How can you fit a giraffe, 2 dogs and a swan into a standard laboratory beaker?!

 

 5.13 Starter 2

·         Use particle theory to explain why the gas in the balloon contracts

Explanation

·         The temperature of the gas inside the balloon decreases so the average speed of the particles decreases

·         Consequently the gas particles collide with the walls of the balloon with less force and less collisions per second

·         Because the walls of the container are flexible, the  volume decreases

 

 

 

5.13 Charles' law

28 October 2011

11:10

·         5.13 understand that there is an absolute zero of temperature which is –273^oC

	<<Charles' law interactive experiment.swf>>
			Open the Charles' law interactive experiment ·         Adjust the temperature ·         What’s the relationship between temperature and volume? ·         Plot a graph of V against T ·         Take a screen shot of the graph

 

 

5.13 results and conclusion

28 October 2011

11:10

Conclusion

·         Volume is directly proportional to absolute (Kelvin) temperature

·         V α T

See the full gallery on Posterous

Charles' law interactive experiment.swf Download this file

5.11

5.11 Starter

·         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 understand the significance of Brownian motion

	<<Video - Model of Brownian motion.wmv>>

Model 1

·         What does the red puck represent?

·         What do the metal balls represent?

			<<brownian_motion.swf>>

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

1.   Draw the path of a smoke particle in air  (3 marks)

Start

Finish

2.   Explain what is meant by Brownian Motion of smoke particles in air and how it provides evidence for air particles  (4 marks)

Brownian motion is the random motion of a particle. As for this ,the smoke particle has a random motion. As (invisible) air molecules collide with the smoke particle, they push it about in different directions at random.

Answer

•         We can see the large smoke particles

•         We can’t see the much smaller air particles

•         But the smoke particles move when the air particles collide with them

•         So the movement of the smoke particles is evidence for the existence of air particles

3.   What change would you expect to see in the movement of the smoke particles if the air was cooled down?  Why?  (2 marks)

Slow movement for the smoke particle because the (invisible) air particles have less kinetic which means less vibration so it would collide to the smoke particle less often.

Answer

•         The smoke particles would move slower

•         Because the air particles are moving slower and hitting them with less force

See the full gallery on Posterous

brownian_motion.swf Download this file

Next Physics e-lesson 5.12+5.15

 16:15

	<<Video - simulation of gas pressure in Phun.flv>>

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

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

1.    How do the particles create a pressure?

The particles is moving quickly and colliding to the surface of the wall

2.    If you increase the temperature, how does the movement of the particles change?

The particles vibrate fasters

3.    If you increase the temperature, how does the number of collisions per second change?

Number of collisions increase

4.    If you increase the temperature, what does this do to the pressure?

Increase the Pressure

 

 

5.12+5.15 Plenary

02 November 2011

15:55

<<Ideal gases - summary of terms.pptx>>

Ideal gases - summary of terms.pptx Download this file

5.9 and 5.10 Answers

5.9 and 5.10 answers

 

 

 

5.7 and 5.8 Starter answers

28 October 2011

11:00

·         What are the 6 processes shown by the arrows?

		Melting
	Boiling

 

 

 

5.7 and 5.8 Answers

28 October 2011

10:20

·         Collins p.112

1a

·         Particles in a solid are strongly bonded to each other so their particles are held in a fixed, regular pattern and can not move

·         The bonds between particles in liquids and gases are weaker and therefore their particles can move relative to each other

 

1b

·         The particles in solids and liquids are closely packed and they are therefore incompressible

·         The particles in a gas are very widely spaced and the forces between them are very weak so they can spread out to fill their container

Boiling

·         Boiling occurs when you heat a liquid until the average energy of the particles is great enough for them to turn into a gas

·         Boiling occurs at a fixed temperature called the boiling point

·         Boiling occurs throughout a liquid

·         It is a fast process

·        

 

Evaporation

·         Evaporation occurs when a liquid is left open to the air

·         Only particles at the surface of the liquid that have enough energy can escape the liquid into the air

·         Evaporation occurs for a range of temperatures; high temperatures increase evaporation, low temperatures decrease evaporation

·         Evaporation only occurs from the surface of a liquid

·         It is a slower process

·         Because it removes the most energetic particles from a liquid the average energy of the remaining particles is decreased and the liquid cools down

·        

5.7 and 5.8

What are the 6 processes shown by the arrows?

 

Solid -----> Liquid = Melting             

Liquid----->Gas = evaporation/boiling

Gas-------->Liquid = Condensation

Liquid------> Solid = freezing

Solid -------->Gas = sublimation

 

·         5.7 understand that a substance can change state from solid to liquid by the process of melting

·         5.8 understand that a substance can change state from liquid to gas by the process of evaporation or boiling

·         Questions from Collins p.112

·         Answer in Bullet Points!

Q1 a)solid keeps their shape because all particles are packed tightly

b)solid and liquids have fixed volume because there are still some intermolecular force whereas in gases all the particles are separate

·         Evaporation occurs for a range of temperatures; high temperatures increase evaporation, low temperatures decrease evaporation

·         Boiling occurs when you heat a liquid until the average energy of the particles is great enough for them to turn into a gas.

·         Boiling occurs at a fixed temperature called the boiling point.

Use following pages from Collins as a resource to help you

 

 

5.7 and 5.8 Experiment - Cooling Curve of Stearic Acid using datalogger

15 October 2010

14:34

 

 

states of matter drag and drop plenary.swf Download this file

Fill the trucks - Properties of s,l,g.swf Download this file