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TGI3:
Mixtures which are not solutions
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We have shown some everyday examples. The basic mixture of
states applies, but really there are more than two substances
involved.
Language Alert
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Some books make statements such as, ‘everything
is solid, liquid or gas’, but this is misleading. |
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Samples of mixtures such as pastes, gels, emulsions,
foams and mists do not show the clear characteristics
of one state. |
Attempts to force students to classify everything as one of
solid, liquid or gas are problematic for several reasons:
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The idea of a state can only sensibly be applied to
pure samples of substances, so we cannot say that ‘everything’
must be a solid, a liquid or a gas.
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Such statements
do not recognise the distinction between stuff that
is a pure sample of a substance and stuff that is a
mixture of substances |
They could be taken to mean that solid, liquid and gas are
three types of stuff rather than three possible states a pure
sample of a substance could be in.
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Science Enhancement Programme CD-ROM 2005 |
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user
guide |
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