P5- Improvement Plan

Improvement Plan - P5.doc Download this file

5.19 Boyle's Law (Corrections in yellow)

5.19 Boyle's Law

·         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 [m³ or 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)

 

 

5.19 Boyle's Law demos

	<<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 Ideal graph and conclusion

 

 

5.19 Questions

07 November 2011

14:52

PFY, p.36, Q.1a, 3 and 4

Extension: PFY, p.36, Q.5.

5.  

Part 1:

       p1v1=p2v2 (T is constant)

      2.5atm* 1000 cm cubed= 1 atm*v2

      v2= 2500 cm cubed

Part 2:

      

    Pressure in tyre and pump: 1 atm

    Volume of tyre and pump: 1,100 cm cubed

    Volume of tyre and empty pump: 1,000 cm cubed

    p1v1= p2v2 (T is constant)

    1 atm* 1,100 cm cubed= p2* 1,000 cm cubed

    p2= 1.1 atm

5.18

5.17 Demo

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

·         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

 

 

5.18 Question

Collins, p.116

p1/T1=p2/T2

3/293=p2/328

p2= 3.4 bar

 

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

The pressure decreases.

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

As the temperature decreases, the average kinetic energy of the particles decreases. This means that they move around with less energy. This would mean that they hit the container with less force and less frequently.

5.16

5.16 Virtual Experiment

·         5.16 understand that the Kelvin temperature of the gas is proportional to the average kinetic energy of its molecules

1.       Volume remains constant throughout this experiment.

2.       When the temperature is increased the pressure increased. This is because the particles have more energy from the heat and so they moved faster.

3.       It is not proportional because the gradient is decreasing in the graph.

4.       It is proportional because it is proportional in the graph.

5.       The word average is used because some particles can be moving at a higher or lower speed although most of them are around the average.

See the full gallery on Posterous

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

5.14

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: TK = ToC + 273

Converting Kelvin to Centigrade: ToC = TK - 273

TK = Temperature in Kelvin [K]

ToC = Temperature in Degrees Centigrade [oC]

5.14 Questions

· Collins p.118

1. How does kinetic theory explain the idea of absolute zero? Absolute zero is the point where no heat can be removed from the system. Using kinetic theory, we can explain that at absolute zero no particles should have any energy to move since there is no heat. 2. a) Convert these temperatures from Degrees to Kelvin:
1. 20 --> 293
2. 150 --> 423
3. 1000 --> 1273
b) Convert these temperatures from Kelving to degrees: 1. 300 --> 27
2. 650 --> 377
3. 1000 --> 727

5.13

5.13 Starter

· 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

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

>

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

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[cid:image002.png@01CC9EF1.310E7600]

Conclusion
· Volume is directly proportional to absolute (Kelvin) temperature
· V α T

Charles' law interactive experiment.swf Download this file

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5.11

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)

brownian_motion.swf Download this file

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Answers to 5.11.docx Download this file

5.12+5.15 (Corrections in yellow)

1. How do the particles create a pressure?
The particles create pressure by colliding with the walls.

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

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

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

Ideal gases - summary of terms.pptx Download this file

Untitled

Pressure of fresh water= 1,000 kg/m cubed

g= 10N/ kg

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

5. Change in pressure= h*p*g
250,000 – 100,000= h* 1000 * 10
h= 15m

If he was diving in sea water then, h would be more as from the equation:
Change in p= same, g= same, p= less so h= more

6. p=0.42 g/ cm cubed= 420 kg/ m cubed
Change in pressure= h*p*g= 50 *420*1.4
Change in pressure= 29kPa
1.6 bar= 160,000 Pa 29,000 + 160,000= 189,000 Pa= 19 kPa