The concept of molecule
allows to give
a more precise definition
of mixtures and
substance is a substance (solid, liquid or gas) that consists only of
one kind of molecule.
- Distilled water is a pure substance because it consists only of water
- Dioxygen is a pure substance because it consists only of dioxygen
A mixture is
a substance (solid, liquid or gas) which consists of several kinds of
- Air is a mixture because it consists of several kinds of molecules:
dioxygen, dinitrogen, carbon dioxide etc..
- The sugar water is a mixture because it consists of two kinds of
molecules: water and sugar (saccharose).