2. Describing a gas LOs
To do
List the ways in which we can describe the
• amount of a gas
• the physical conditions it experiences.
You might have listed:
n – the number of moles
N – the total number of molecules
mg – the mass of gas (m – the mass of a gas molecule, so mg = N.m)
p – pressure
V – volume
T – absolute temperature
Thermal physics
3. Lesson focus
• The gas laws
Learning objectives
At the end of the lesson you will be able to:
• state Boyle’s law;
• select and apply pV/T = constant.
Thermal physics
4. Learning outcomes
All of you should be able to
• state Boyle’s law correctly;
• make sensible predictions for the variation of V against T, and p against T;
• safely and carefully carry out practical work;
• describe in words the variation of V against T, and p against T.
Most of you should be able to
• describe using symbols the variation of p vs V, V against T, and p against T
Some of you may be able to
• extrapolate the variation of V against T, and p against T and draw appropriate
conclusions.
Thermal physics
5. Gas law no. 1: Boyle’s law LOs
To do
Write a statement of Boyle’s law on your ‘post-it’ note.
1. Draw a graph of p (x axis) against V (y axis).
2. Describe the relationship between p and V.
3. How should these variables be plotted to obtain a straight-line
graph?
Thermal physics LO1: state Boyle’s law
6. Investigating the effect of pressure on the volume of a gas LOs
To do
1. Construct a table for results [headings:
p, V, 1/V] and decide on the correct
units. trapped air
2. Record data as the demonstration
proceeds.
3. Plot a graph of p (independent variable) oil
against V.
4. Describe the relationship between p
and V.
5. Plot a second graph to show a straight-
line (linear) relationship between two
quantities.
Spreadsheet
Thermal physics LO1: state Boyle’s law
8. Gas law no. 2: p vs T LOs
To do
1. Make a prediction to describe the effect of changing
temperature on the volume of a fixed amount of gas.
2. Draw a graph of T (x axis) against V (y axis).
3. Describe the relationship between T and V.
Thermal physics
9. Investigating the effect of temperature on the volume of a gas
LOs
To do
1. Construct a table for results - decide
on the correct headings and units.
2. Record data as the demonstration
proceeds.
3. Plot a graph to show the results.
4. Describe the relationship between the
variables.
Thermal physics
11. Gas law no. 2: ? vs ? LOs
To do
1. Make a prediction to describe the effect of changing
____________ on the ________ of a fixed amount of gas.
2. Draw a graph of ___ (x axis) against ___ (y axis).
3. Describe the relationship between __ and __.
Thermal physics
12. Investigating the effect of temperature on the pressure of a gas
LOs
To do
1. Construct a table for results - decide
on the correct headings and units.
2. Record data as the demonstration
proceeds.
3. Plot a graph to show the results.
4. Describe the relationship between
the variables.
Thermal physics
