Pressure in Gases
13/06/17
23/2/15
Key words: Implode, Pressure, Collide, Temperature, Particles
Starter: In this lesson we will be talking a lot about gas
particles in the air. Describe what they are doing right now
EXT: The picture on the right is what happens to a balloon when you put it in the
fridge for 3 hours. Why does a balloon shrink?
FREEZER for 3 hours
Keywords: Implode,
Pressure, Collide,
Temperature, particle
Learning objectives:
 Understand how particles
affect pressure
 Explain using pressure why a
can collapses
Did you know… if you took a bag of crisps
On a plane, after take off the bag would
have expanded?
Right now in this classroom there are gas particles
moving and colliding. They are always moving!
When they hit into you they cause a force. This
causes a pressure on you.
What is gas pressure caused by?
This pressure is the same for everyone
and it is the same on every part of
your body.
The air pressure is affected by two things…
Quantity
Temperature
The higher
you
go up athe
mountain
the less
pressure
There
are less
particles
higher you
go. Less
force
is. Why?
is exerted on you, there
therefore,
there is less pressure.
Up a mountain
Ground Level
This is why a balloon which hasn’t been blown up
fully is crinkled. It has a small amount of particles so
it has a low pressure
Low
Pressure
High
Pressure
Moving
colliding
which exerts
a force on us
SO…and
what
are particles
doing again…?
Can you
tell me
theare
pressure
difference
if I showed
Because
there
less particles
higher
up
you
picture?
thethis
mountain.
Lower
Pressure
Higher
Pressure
The air pressure is affected by two things…
Quantity
Temperature
Particles move faster as the temperature is increased
= More pressure
If it is cold the particles slow down which produces
less pressure.
So can you explain the balloon example picture?
Activity: Complete you sheet which assesses your
progress of the learning so far
EXT: Can you use your knowledge to explain the ‘Did you Know’
Did you know… if you took a bag of crisps
on a plane, after take off the bag would
have expanded?
cv
cv
It has slowed them down
cv
inflated
Colliding
Balloon
pressure
EXT: Can you use your knowledge to explain the ‘Did you Know’
Did you know… if you took a bag of crisps
on a plane, after take off the bag would
have expanded?
As you take off you are going into less pressure atmosphere.
Less pressure on the outside of the bag means there is
more pressure on the inside relative to the outside so the bag expands.
Activity: Copy and complete this word paragraph
Keywords: higher, pressure, fast, more,
number, particles, less
particles





fast
Gases are made of ----------- that move -------number
The -------of the particles hitting the sides of
pressure
the container causes the --------.
More particles means more pressure
------higher
Faster moving particles means --------pressure
Water liquid exerts less
____ pressure than water
vapour
Learning objectives:
Keywords: Implode,
Pressure, Collide,
Temperature
 Understand how particles
affect pressure
 Explain using pressure why a
can collapses
Why does a can
do this?
There is more pressure inside
the can than outside so the gas
quickly moves which causes spray
Which can has more pressure. Can you explain?
The can on the left has more pressure inside because
the particles inside are a higher temperature
Collapsing Can Experiment
Method
Meth
1. Add a small amount of H2O to the inside of the can
2. Heat the can until steam is produced. Wait 20 s
3. With tongs grab the can and tip upside
Down into cold water
Meth
Collapsing Can Experiment
Meth
Look what happens when you place
a hot can into some cold water
First
Before the experiment there was an equal
pressure between the can and outside
Second
As the can is heated the gas is
expelled and then the water turns
steam which increases the pressure
on the sides of the can.
Finally
When the can is put into cold water the water vapour
quickly condense back to water liquid which quickly
reduces the pressure compared to the outside
The pressure of the outside overwhelms the
pressure on the walls of the can so it crushes
Activity: Use your knowledge of pressure to explain why the
can is crushed
1.Meth
Explain what they did in the experiment
2. Use the sheet to explain the can crushes
when put in cold water.
TASK: Use the words above each picture to explain that part of
the experiment.
Pressure
Outside
Inside
Equal
Can
Heating
Increase/decrease
Pressure
Walls of the can
Cold water
Water vapour
Condense
Decrease
Pressure
Walls of the can
surroundings
implosion
Review
1. The pressure outside and inside the can are equal
2. Heating increases the pressure on the walls of the can.
3. When the can is placed in cold water the water vapour
condenses. This decreases the pressure on the walls of the
can. The surrounding pressure is higher which cause an
implosion of the walls of the can.
Pressure
Outside
Inside
Equal
Can
Heating
Increase/decrease
Pressure
Walls of the can
Cold water
Water vapour
Condense
Decrease
Pressure
Walls of the can
surroundings
implosion
Learning objectives:
Keywords: Implode,
Pressure, Collide,
Temperature
 Understand how particles
affect pressure
 Explain using pressure why
a can collapses
Plenary
1. Which of these is under greater
pressure?
2. Complete the sentence
“Right now particles are…?
3. The pressure of a gas is affected by
what two things?
4. Which can has the higher pressure and why?
5. True/False: The balloon would expand if I took it
up the mountain?
6. True/False: There is a different pressure on you sat
down than me stood up?
6. What is wrong with this picture?
7. What happens to the pressure on the inside of a
can when you put it in cold water?
1. Which of these is under greater
pressure?
2. Complete the sentence
“Right now particles are…?
Moving
&
Colliding
3. The pressure of a gas is affected by
what two things?
Quantity
Temperature
4. Which can has the higher pressure and why?
Because it is warmer the particles
move faster
5. True/False: The balloon would expand if I took it
up the mountain?
TRUE
6. True/False: There is a different pressure on you sat
down than me stood up?
FALSE
6. What is wrong with this picture?
No arrows showing the movement of particles
7. What happens to the pressure on the inside of a
can when you put it in cold water?
Lower Pressure