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TGI1:
Dissolving
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LINKS |
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Notes on the videos of four substances being added
to water
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Sugar.
This dissolves. There are no pieces of sugar left. The
mixture is clear.
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Chalk.
This does not dissolve. You can still see bits of chalk.
The mixture is not clear.
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Glycerine.
This dissolves. There are no blobs of glycerine left.
The mixture is clear.
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Oleic acid.
This does not dissolve. You can still see blobs of oleic
acid.
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Notes on the animations showing a grain and a droplet
dissolving
Students need to understand that a ‘grain’ or
‘blob’ would contain millions of particles, but
we can only show a small number in an animation. Similarly,
the ‘time-lapse’ sequences show the particles
spreading out over time rather than the collisions which cause
this to happen. As with gases, the key point is that dissolving
results in clear solutions because there are too few particles
of solute grouped together for us to be able to see them.
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Science Enhancement Programme CD-ROM 2005 |
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user
guide |
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