Salts can be Anhydrous or Hydrated
- All solid salts consist of lattice positive and negative Ions
- In some salts, water molecules are incorperated in the lattice too
- The water in the lattice is called water of cystallisation
- A solid salt containing water of crystallisation is Hyrdrated
- If the salt doesnt contain any water of crystallisation, it's call Anhydrous
The water molecules in hydrated salts have a small positive charge on the hydrogen atoms and a small negative charge on the oxygen atoms. This means they are attracted to the ions in the lattice and are held in place.
You can calculate How much water of crystallisation a salt contains
- One mole of a Hydrated salt always has a particular number of moles of water of crystallisation- It's formula shows how many
For example Hydrated copper sulfate has 5 moles of water for every one mole of salt- so it's formula is CuSO4.5H20
- Many hydrated salts, when heated, lose their water of crystallisation, to become Anhydrous.
- If you know the mass of the salt when it's hydrated and when it's anhyrdous you can work out it's formula
That is it for part 1!