Question

Question #fc437

Answer 1

Sugar dissolves in water because its `"OH"` groups form strong hydrogen bonds with water.

Explanation:

The formula for sucrose is

It contains eight `"O-H"` groups.

The oxygen atoms are slightly negative, and the hydrogen atoms are slightly positive.

That is, the `"O-H"` bonds are polar.

Sucrose molecules are attracted to each other in the crystal because of the dipole-dipole attractions among the `"O"` atoms in one molecule and the `"H"` atoms in the neighbouring molecules (hydrogen bonds).

If we add water to sucrose, the `"O-H"` groups in the water form hydrogen bonds to the sucrose molecules in the crystal.

In turn, the sucrose molecules use their `"O-H"` groups to form `"H"`-bonds with the water molecules.

We see below a picture of water molecules attacking the surface of sucrose.

The water molecules surround the sucrose molecules, replacing the sucrose-sucrose `"H"`-bonds with sucrose-water `"H"`-bonds.

Eventually, the sucrose molecules leave the surface of the crystal and disperse themselves throughout the water as hydrated sucrose molecules.