Question #fc437

1 Answer
Oct 29, 2016

Answer:

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

Explanation:

The formula for sucrose is

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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.

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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.

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