States of Matter – D. Franklin
Equipment
Balloons
Water and Ice cubes
kettle
hairdryer
Beakers
Tape measure
Health and Safety
Hot water from the kettle
Balloons will pop!
Latex allergy could be an issue for some pupils
Ice cubes and water could form a slippage problem if allowed to fall on the floor
Initial discussion of solids, liquids and gases
Call for a small group of volunteers. Firstly allow them to move/dance round in a random pattern.
Explain that they are now all atoms in a gas. Perhaps give a very basic explanation of atoms,
molecules and bonds? Next get them to hold hands in a group, explain how their movement is now
more limited though each group can still move about, and explain that this might represent a liquid.
Now get the group to stand linked together and tell them they cannot move. Now they represent a
solid. Explain that if we give the material energy, in this case in the form of heat, the molecules and
bonds will start to move about, if we give them enough energy, the bonds will break and the
molecules or atoms will be free to move around again, like gases.
The ice cubes, water and steam from the kettle can be used to show these three states of matter in
water.
Now take a glass of warm water and drop an ice cube into it. What happens? The ice should break
or at least crack very noticeably. Explain that this is because the bonds in the ice could not respond
(stretch and move) quickly enough to the energy gained from the warm water and so they broke.
(You could then take a glass of very cold water and show that an ice cube dropped into that does not
(hopefully!) break in the same way.)
Balloons can be used to show how volume changes as we put energy into gases.
If you can get a bucket of ice/ice cold water; you should be able to show that an inflated balloon
shrinks a little as you cool the air inside it down. It may be easier to see it expand as it warms up
after you remove it from the ice. This works much better with liquid nitrogen but iced water ought
to give a visible effect. If you have access to a freezer compartment in a fridge (prep-room?) you
can half inflate a balloon, pop it in the freezer compartment and then let the students see it expand
as it warms up.
Similarly, with a bit of luck, using a hairdryer you should be able to (gently) warm up a half inflated
balloon to show an increase in size. The increase in size can be measured by using a tape measure
around the balloon. Another alternative is to try to put a slightly inflated balloon into a large beaker
of hot water. As the air inside the balloon heats up it will expand and so displace more water.
You could then show a clip from the internet of hot air balloons and explain that warm air is less
dense than cold air as the particles gain energy and spread out more. (For older children perhaps a
Chinese paper lantern balloon could be used, the air in it heated by a hairdryer rather than by using
a naked flame?) There are lots of examples in the links below.
There is a very useful experiment of this type at
http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p077.shtml#procedure
Useful links
http://science.howstuffworks.com/transport/flight/modern/hot-air-balloon.htm
Another method you could show expansion and contraction of gases
http://www.youtube.com/watch?v=nXOIL8beKUo
Some similar and simple experiments can be found at
http://www.scienceinschool.org/2012/issue24/energy
Primary science resources
http://www.opalexplorenature.org/learning
http://www.primaryresources.co.uk/science/science3a2.htm
http://www.tes.co.uk/ks1-science-primary-teaching-resources/
http://www.bbc.co.uk/bitesize/
http://tag.wonderhowto.com/make-a-paper-bag-hot-air-balloon/