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TGM10:
Identity of a substance
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Notes on the concept of same substance from two different
starting points
This point is emphasised here because some students may link
the idea of a substance to its ‘history’ –
how it was formed – rather than its properties: they
would not regard copper oxide formed by the decomposition
of copper carbonate and copper oxide formed from the reaction
of copper with oxygen as the same substance.
You can read more about students’ ideas in 'Key
Features of Students' Understanding' also in the Teachers’
Guide.
Notes on the video of blue copper sulfate being heated
Students should notice that
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the
blue crystals turn white at the edges as they are heated,
but by the end they have become crumbly and white all
the way through |
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clear, colourless
liquid forms in the cooler part of the test-tube and
is collected via the delivery tube. Students should
be able to suggest that we could show that this sample
is water by heating it to find the boiling
point. |
Note on the word equation
It is debatable whether this is a chemical change or a separation
of substances. So long as we know what has happened it doesn’t
really matter.
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end of the ‘Foundation Topics’ section of
the Teachers’ Guide. |
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Clicking the forward arrow in the Teachers’ Guide will
take you to the notes related to the next topic.
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Science Enhancement Programme CD-ROM 2005 |
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user
guide |
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