Why does sugar disappear in water but sand just sits there?
Two little spoons… one sugar, one sand. Water is full of tiny grabby helpers. Stir the sugar in and it seems to disappear — but where did it go? Is the sugar gone forever now… or is it still in there, hiding too small to see? Take a guess, then we'll look closely and find out!
After you watchWhy does sugar disappear in water but sand just sits there?
The short answer
Sugar vanishes because water grabs each grain and peels it into bits too small to see, then spreads them through the whole glass. The sugar isn't gone — the water now tastes sweet. Sand grains hold each other too tightly for water to peel apart, so they stay in a pile on the bottom.
The whole story
How it works
Water is made of countless tiny jiggling bits that have a slightly sticky side. Sugar is sticky to water, so the water grabs each grain, pulls it off the pile one piece at a time, and carries it all through the glass — that's dissolving. Sand grips its own pieces far harder than water can pull, so water slides right off and the sand settles in a pile.
What people get wrong
Kids think dissolving makes the sugar disappear for good. It doesn't — every piece is still in the glass, just spread out too small to see. The water weighs more and tastes sweet. Nothing was destroyed.
Questions kids ask
If the sugar disappears, where did it go?
Nowhere! It's still in the glass. The water broke it into bits too small to see and spread them out, so the water now tastes sweet.
Why does the sand stay in a pile?
Sand grains hold onto each other too tightly. The water can't peel them apart, so they slide down and sit on the bottom.
Keep going
What else makes you wonder?
- What else in the kitchen would vanish like sugar, and what would just sit like sand?
- If you can't see the sugar but the water tastes sweet, where is it hiding?