Question #fc437

1 Answer
Ernest Z.
Oct 29, 2016

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

Explanation:

The formula for sucrose is

upload.wikimedia.org

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.

www.middleschoolchemistry.com

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.

antoine.frostburg.edu

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