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Broken up, not vanished

Where Does Sugar Go in Water?

Dissolving pulls a solid apart into individual molecules spread through the liquid.

1 A sugar crystal2 Water pullsmolecules offone by one3 They spreadevenly — toosmall to see
Still there. Just individually.

  1. Step 1 of 5

    The sugar is still present.

    Mass checkWater plussugar beforeSolution after— identical

    Weigh the water before and after and it is heavier by exactly the sugar's weight. Nothing was destroyed — you can taste it.

  2. Step 2 of 5

    Water molecules pull the crystal apart.

    The crystal surface Water molecules pullingoff single molecules

    Water surrounds the crystal's surface and tugs individual molecules away. Each one drifts off separately into the liquid.

  3. Step 3 of 5

    Individual molecules are invisible.

    Crystal Big enough to scatterlight — visibleSingle moleculesFar smaller than light— invisible

    A sugar molecule is far smaller than a wavelength of light, so it cannot scatter light or be seen. Spread out, it disappears from view.

  4. Step 4 of 5

    Stirring and heat make it faster.

    Hot and stirredsecondsCold and stillmany minutes

    Stirring brings fresh water to the surface; heat makes molecules move harder. Neither changes what happens, only how quickly.

  5. Step 5 of 5

    There is a limit.

    Below the limit All dissolvesAbove it The excess stays solid

    Once the water holds as much as it can, extra sugar just sits at the bottom. Hot water holds more, which is why it drops out as it cools.

    Not everything dissolves in water. Oil molecules are not attracted to water at all, so water cannot pull them apart.

The short version

Dissolving pulls a solid apart into individual molecules spread through the liquid, which is why it seems to vanish.

Try it yourself

Weigh a glass of water, stir in a spoon of sugar, and weigh again. The extra weight is exactly the sugar.

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