5.16 Questions

Answers:

1.           The number of moles of gas and volume

2.           The pressure increases because the particles have more kinetic energy when they are heated, therefore more collisions to the walls of the container are caused with more force and more frequency.

3.           No, temperature is proportional to  average speed (m/s)2 not (m/s)

4.           Yes, it is because (m/s)2 is proportional to Kinetic energy, and from our graph we see that (m/s)2 is also proportional to temperature. Therefore temperature is also proportional to Kinetic Energy.

5.           The word “average” is used because the particles in the container have a range of speeds and therefore a range of K.E’s.

5.11

Instructions for Objective 5.11

1.    5.11 Starter.  Watch the video and think about the question.  No need to type anything.

2.    5.11.  Watch the videos and animations for the 3 models of Brownian Motion (for Model 3 you need to open the attached).  Think about the questions.  No need to type anything. 

3.    5.11 explained.  Check your understanding with the model answers.

4.    5.11 Questions.  Forward this e-mail to your blog and complete the questions.

5.    Answers to step 2 will be sent separately.  Don’t look at them until you’ve done the work!

 

 

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?

			<<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)

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

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

See the full gallery on Posterous

brownian_motion.swf 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

Answers:

 

Q1:  Absolute zero (-273 degrees) is when the particles CANNOT move anymore, they have no more kinetic energy.

Q2: i) 20+273 = 293K     ii) 150+273 = 423K     iii) 1000+273 =1273K       

Q3: i) 300-273 =  27degrees    ii) 650-273 =  377degrees    iii) 1000 - 273 = 727 degrees

Obj: 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

02 November 2011

18:17

·         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

·         (gas is at constant pressure - flexible container)

·         V α T

 

 

5.13 Plenary

02 November 2011

19:13

http://phet.colorado.edu/en/simulation/gas-properties

Instructions

·         Keep the Pressure constant (flexible container)

·         Pump some gas particles in

·         Predict what will happen when you heat the gas.  Try it.

·         Predict what will happen when you cool the gas.  Try it.

 

Question

·         What would happen to the volume of the container if you could cool the gas to absolute zero, 0K?

It would DECREASE

·        

See the full gallery on Posterous

Charles' law interactive experiment.swf Download this file

Gas Properties Simulation

Click to Run

5.9 and 5.10

 

5.9 and 5.10 starter

28 October 2011

12:01

Tell the person next to you…

·         How do particles in move in a solid, a liquid and a gas?

·         Describe…

o    speed of particles

o    relative position of particles (fixed or not)

o    pattern of particles (regularly arranged or not)

o    size of the particles

o    space between the particles

o    strength of bonds between the particles

			Use the animation to verify your answers

 

 

 

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
S____		·         c_____y packed ·         regular p_____n	·         v______e about a fixed position	·         f____d shape ·         not easily c_________d since particles are closely p______d ·         Strong bonds
L____		·         c_____y packed ·         no p_____n	·         free to f___w over each other	·         takes shape of its c_______r ·         can be p_____d ·         not easily c_________d since particles are closely p______d ·         Weak bonds
G___

5.6

Instructions for Objective 5.6

1.    5.6. Read the objective.  Learn the formula and units.

2.    5.6 Demo.  Read the explanation of the picturre

3.    5.6 Questions.  Forward this e-mail to your blog.  Type your answers under the questions.  (This questions are challenging – don’t give up though!)

4.    5.6 Plenary.  Type your answer under the question.

5.    Answers to steps 3 and 4 will be sent separately.  Don’t look at them until you’ve done the work!

 

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

?

Mr. Baker’s Answer:

∆p = h × ρ × g

250,000 - 100,000 = h x 1,000 x 10

h = 15m

?

Mr. Baker’s Answer:

ρ = 0.42g/cm³ = 420kg/m³

 

∆p = h × ρ × g

∆p = 50 x 420 x 1.4

∆p =29,400Pa or 29kPa

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.

5.5

 

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

 

5.4 - Written Questions

Question 1 A:

·      They have a large surface area so the amount of P can be spread around equally

·      Therefore there is less pressure on one area of the snow

Question 2 A:

·      For the same reason that Inuits wear snow boots. The bigger the S.A of the tyre, the more the P=F/A is spread around so it is the same P amount all over.

·      Therefore the tractor will not sink and get stuck in the mud.

5.4 Pressure Questions

5.4 Pressure Questions

07 October 2011

11:47

·         PFY p.91, Q.3 and 7.

 P= F/A = 100,000 = x/10

F = 1,000,000N = 1MN

a)              P = F/A = 500/5 = 100 N/m^2

b)              P = F/A = 500/20 = 25 N/m^2

 

5.4

·         5.4 recall and use the relationship between pressure, force and area:

        pressure = force / area

                  p = F / A

5.4 Starter Explained

<<animation - why a drawing pin works.swf>>

 

·         Your finger pushes on the pin and the pin pushes back on your finger

·         N3L tells us that all these two forces are equal in size

·         The pin pushes on the wall and the wall pushes back on the pin

·         N3L tells us that all these two forces are also equal in size

·         If the surface area is large then the force is spread over a large area and the pressure is low

·         If the surface area is small then the force is spread over a small area and the pressure is high

·         You would like the pressure on your finger to be low and the pressure on the wall to be high

·         The other way round is painful!