text: Hydrates are ionic compounds that have absorbed water. They are named as the ionic compound followed by a numerical prefix and -hydrate. The numerical prefixes used are listed below (see IUPAC numerical multiplier):
  # mono-
  # di-
  # tri-
  # tetra-
  # penta-
  # hexa-
  # hepta-
  # octa-
  # nona-
  # deca-
  For example, CuSO·5HO is "copper(II) sulfate pentahydrate".