5.19 Boyle's Law

5.19 Boyle's Law demos

02 November 2011

20:01

	<<Video - mixing colours in a bell jar with Boyle's law.flv>>

Fun with the vacuum pump!

·         

Marshmellows

·         Food colouring in pipettes

·         Surgical gloves

5.19 Experiment

07 November 2011

14:32

·         

Change the pressure of a fixed mass of gas at a constant temperature

·         Measure the volume

·         Use the EXCEL spreadsheet to analyse your results

Ideal Gas - Boyle's Law.xlsx Download this file

5.14

5.14

28 October 2011

11:10

·         

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 the lowest posible temperature, and at this point the molecules have zero speed which results in zero kinetic energy

q2 A) i) Tk = Toc + 273 = 20+273 = 293k

ii) 150+273 = 423k

iii) 1000+273 = 1273k

b) i) Toc = Tk - 273 = 300 - 273 = 27 degrees

ii) 650 - 273 = 377 degrees

iii) 1000 - 273 = 727 degrees

Untitled

<div style="position: relative; width: 300px; height: 228px;"><a href="http://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlp" style="text-decoration: none;"><img src="

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5.11

5.11 Starter

02 November 2011

16:58

	<<Video - Brownian Motion smoke in air.wmv>>

·         

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

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

Model 1

·         What does the red puck represent?

·         What do the metal balls represent?

red puck = smoke

metal balls = air molecules

			<<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

02 November 2011

17:21

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

you cannot because smoke particles move about randomly depending on when it hits the air particles

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 - the movement of small particles as a result of continuous contact with molecules in the same space

3. 

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

you would expect them to move slower because as you cool it down the particles move slower thus more collisions are caused

brownian_motion.swf Download this file

e-lesson 5.12+5.15

Best wishes,

Mr B

5.12+5.15 Starter

02 November 2011

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?

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

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

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

5.5 & 5.6

5.5

07 October 2011

10:40

·         

5.5 understand that the pressure at a point in a gas or liquid which is at rest acts equally in all directions

5.5 Demo 1 - Magdeburg Hemispheres

12 October 2011

07:19

·         Magdeburg Hemispheres

 

·         The original experiment was done by using two teams of wild horses to try and pull the hemispheres apart

·         And here are the horses I was talking about!

5.5 Demo 2 - Collapsing Bottle

12 October 2011

07:19

·         Collapsing Bottle

 

5.6

07 October 2011

10:40

·         

5.6 recall and use the relationship for pressure difference:

 

        pressure difference = height × density × g

                               ∆p = h × ρ × g

 

 

∆p = pressure of the fluid (N/m² or Pa)

h = height of the fluid (m)

ρ = density of the fluid (kg/m³)

g = gravitational field strength (N/kg)

5.6 Demo - squirting water column

12 October 2011

07:24

·         The bottom hole squirts water the furthest

·         Because the water at the bottom has the greatest pressure

·         Because in the formula ∆p = h × ρ × g, ρ is constant, g is constant and h is large

·         So ∆p = large

5.6 Questions

07 October 2011

11:53

Collins, p.107

Q5) 

 

5.             p=hxpxg

150000 = hx1000x10

h=15m

 

6.             ρ = 0.42g/cm³ = 420kg/m³

 P=hxpxg

P =50x420x1.4

P =29,400Pa

 1,000mbar = 1 bar = 100,000Pa

1.6 bar = 160,000Pa

 

So total pressure = 29,000+160,000 = 189,000Pa 

Notes:

ρ_{fresh water} = 1,000kg/m³

g = 10N/kg

1,000mbar = 1 bar = 100,000Pa

5.6 Plenary

12 October 2011

07:23

·         

Which diver experiences the greatest pressure?

 

They both experience the same pressure, because they are down at the same depth.

5.9 and 5.10

5.9 and 5.10

28 October 2011

10:21

·         

5.9 recall that particles in a liquid have a random motion within a close-packed irregular structure

·         5.10 recall that particles in a solid vibrate about fixed positions within a close-packed regular structure

·         Complete the missing words in the table below

·         Cut and paste the particle images into the table

State	Particle Picture	Arrangement of Particles	Motion of Particles	Other Properties
solid		·          closely packed

·         regular pattern

·         vibrate about a fixed position

·         fixedshape

·         not easily compressed since particles are closely packed

·         Strong bonds

liquid

·         closely packed

·         no pattern

·         free to flow over each other

·         takes shape of its container

·         can be poured

·         not easily contained since particles are closely packed

·         Weak bonds

gas

·         widely spaced

·         no pattern

·         very fast moving

·         random directions

·         fills its container

·         can be poured

·         easily compressed since its particles are far apart

·         Very weak bonds

s,l,g animation.swf Download this file