Wine Analysis Home
- The term mole is derived from the word molecule.
- Like atoms, molecules are so small that a very large number of molecules are involved in reactions etc.
- The unit mole is used by chemists to represent a large number of molecules in the same way that a baker uses a dozen to represent 12 buns, or the way 12 dozen is represented by a gross.
- 1 mole of any substance is 6.0 x 1023 molecules of that substance.
- 6.0 x 1023 is called the Avagadro's number.
- Units such as a mole, atomic weight (AW), molecular weight (MW) or molar solution (M) are all based on the Avagadro's number, and are a convenient way of dealing with such a large number of molecules.
- 1 mole of any substance is its AW (atomic weight) or MW (molecular weight) in grams.
- As examples -
- The molecular weight (MW) of sodium hydroxide is 40.
Therefore 1 mole or 6.0 x 1023 molecules of sodium hydroxide weighs 40 grams.
(The very reason it was assigned a MW of 40)
- A molecule of SO2 is composed of one (1) sulphur (S) and two (2) oxygens (O).
Hence 1 mole of SO2 will contain 1 mole of sulphur (S) and 2 moles of oxygen (O)
or 6.0 x 1023 molecules of S and 12 x 1023 molecules of O.