• Water of crystallisation?is when some compounds can form?crystals?which have?water?as part of their structure
• A compound that contains water of crystallisation is called a?hydrated compound
• The water of crystallisation is separated from the main formula by a?dot?when writing the chemical formula of hydrated compounds
  • Eg. hydrated copper(II) sulfate is CuSO4?5H2O

   

• A compound which doesn’t contain water of crystallisation is called an?anhydrous compound
  • Eg. anhydrous copper(II) sulfate is CuSO4

   

• A compound can be hydrated to?different degrees
  • Eg. cobalt(II) chloride can be hydrated by?six?or?two?water molecules
  • CoCl2??6H2O or CoCl2??2H2O

   

• The conversion of anhydrous compounds to hydrated compounds is?reversible?by heating the hydrated salt

Anhydrous to hydrated salt:

CuSO4?+ 5H2O?→ CuSO4?5H2OHydrated to anhydrous salt (by heating):

CuSO4?5H2O → CuSO4?+ 5H2O