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Q & A: sugar with our tea

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Most recent answer: 10/22/2007
Q:
Why does the level of a cup of tea go down whe you add a
small amount of sugar?
- luke wren (age 11)
UK
A:
I've never heard of that effect. Tea is almost all water. The volume of water goes up when sugar is added, although not by quite as much as the volume of the added sugar. Are you sure the effect is real, or is it just somethig somebody said?
If the effect is real, one could imagine several explanations. Above 4C, water expands as it gets hotter. Adding a little sugar, and especially stirring it in, would cool the water.  If the water started off almost boiling, and got cooled down to luke-warm (no pun intended), it would shrink about 3%. (try googling 'density of water vs temperature'.) Maybe that's what's happening. A little bit of dissolved air might also get released, but I don't think that would be as big an effect.

Mike W.

(published on 10/22/2007)

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