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Asked by Nadi14 to Ceri, Marikka, Matt, Rob, Sally on 15 Nov 2014.
Question: Why can conduction happen through a solid but not through a liquid or gas?
- Keywords:
- conduction,
- gas,
- liquid,
- solid
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Ceri Dare answered on 15 Nov 2014:
Heat is a measure of how much molecules are wiggling around.
The molecules in a solid are all packed together very tightly and almost touching – like in a school assembly. So if one molecule wiggles a bit, then its neighbour wiggles too, and the wiggling passes on like a Mexican wave.
The molecules in a liquid have a lot more room – maybe like a school playground. So if one molecule wiggles, then its neighbour doesn’t wiggle so much because it is not as close. Because there is more room, the molecules can move around – so if a molecule is hot and wiggly, it usually rises to the top of the liquid itself, rather than making the other molecules wiggly.
The molecules in a gas are far apart. So one wiggly molecule doesn’t really affect the other molecules much at all.
This webpage could tell you more: http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/energy/heatrev1.shtml
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Robert Hampson answered on 17 Nov 2014:
Do you mean conducting heat or conducting electricity?
Liquids can conduct electricity especially if they have salts dissovled in them. This is how we do something called electrolysis which is how we produce most of our aluminium.
Conduction of heat doesn’t really work well in liquids because they are too free to move around. In a solid, atoms are close together and when heated they move around more, bumping into their neighbours causing them to also move around more. This movement is passed through the solid and is called conduction. In a liquid, you heat a molecule and it moves around more, but this allows it to move away from the heat source to another area. A colder molecule can then take its place and be heated. This is convection and happens in liquids because of the possibility of circulation.
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