1. Particle Model of Matter
11. Gases – effect of work

2. Today’s lesson goals:
To understand and explain that work is the transfer of energy by a force.
To explain the effect of doing work on a gas on the internal energy and temperature.
To explain everyday phenomena.

3. What is work? 𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆=𝑭𝒐𝒓𝒄𝒆 𝒙 𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆
What is the equation for work?
When you do work what is being transferred?
𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆=𝑭𝒐𝒓𝒄𝒆 𝒙 𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆
Energy, so work is measured in Joules (J)
Lesson Aims:

4. What happens to the energy in a system when work is done?
Think of a swing…
Before the parent gives a push.
After the parent has given a push
When is the energy of the swing system greatest?

5. How can we do work on a gas?
Heating it up – watch the demo, what happens to the volume of the gas when it is heated.
Compressing it – What happens to the air in a bicycle tyre when it is pumped up? Why?

6. What happens when we do work to compress a gas?
Write an answer to the above question explaining what happens and why. You need to talk about:
Kinetic energy of the gas molecules
Internal energy of the gas
Temperature of the gas

7. Whenever we do work on a gas…
We are increasing the internal energy of that gas.
The average kinetic energy of the molecules has increased.

8. PV = Constant?
Choose one of the following real situations and find out why the equation PV = constant does not hold true. Come ready to discuss this at the next lesson.
A pump compressing a gas
A carbon dioxide cylinder being opened.
A camping gas cylinder being used

9. What can be a major issue of using a pump to compress a flammable gas?
Internal energy of gas increases, temperature increases!
If there is any air present….

10. A carbon dioxide cylinder being opened.
If the cylinder is opened very fast, the gas escapes quickly.
In this case the gas is doing work on the surroundings.
What happens to the internal energy of the gas?
What happens to the temperature of the cylinder?

11. A butane gas bottle being opened?
Butane is stored as a liquid under compression.
When the bottle is opened quickly the gas escapes doing work on the surroundings again.
This time the liquid changes state to replace the gas that has left so more energy is taken from the surroundings.
You can see the frozen condensation on the outside of the bottle.

12. Homework
Revise for a test on the Particle Model of Matter topic.

13. How do I revise effectively?
REVISION IS NOT…
Reading your exercise book once or twice. There MUST be another process or you will not learn everything.
Create a revision page / summary
Spider diagram
Note cards with specific information on each card.
Use highlighters / colours to emphasise key points in your NEW notes.
Test yourself, test each other, write out the equations, explain what they mean – teach your parents…sister…dog…
Use revision guide to help create notes / test yourself.
Use websites: Antonine Education, GCSE Bitesize, S-cool pick out the topics we have done & take the tests.
Re-do questions we did in class / HW practice improving your answers (particularly long answer questions).

14. Topics Kinetic Theory – explaining structure (solids, liquids & gases)
Internal Energy – definition & change with temperature
Specific Heat Capacity- E =mcθ – heating substances (need the definition)
Specific Latent Heat – E=mL – changing state.
Density
Conduction, convection & evaporation
Gas Pressure & temperature
Gas – Boyle’s Law
Gas – Work done on a gas.