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Hexahydrate

Hexahydrate is a chemical term used for a compound that contains six water molecules per formula unit in its crystalline form. In a hexahydrate, the water molecules may be coordinated to the central cation as ligands or exist as lattice water within the crystal structure. The designation X·6H2O is applied when crystallization from water yields a stable six-water form, distinguishing it from other hydrates such as dihydrate, pentahydrate, or heptahydrate.

Hexahydrates commonly arise from salts crystallizing from aqueous solutions under conditions that stabilize six waters in

Notable examples include ferrous sulfate hexahydrate (FeSO4·6H2O), known as green vitriol; cobalt(II) chloride hexahydrate (CoCl2·6H2O), which

the
lattice.
They
are
typically
formed
by
transition
metal
salts
and
certain
ionic
compounds.
The
water
of
hydration
can
influence
properties
such
as
solubility,
color,
and
stability.
Dehydration
of
hexahydrates
by
heating
releases
water
and
yields
the
anhydrous
salt
or
a
lower-hydrate
form,
often
with
distinct
changes
in
structure
and
properties.
is
blue
when
hydrated
and
turns
pink
upon
dehydration;
and
zinc
chloride
hexahydrate
(ZnCl2·6H2O).
These
compounds
are
used
as
laboratory
reagents,
in
teaching
demonstrations,
and
in
some
cases
as
humidity
indicators
or
sources
of
metal
ions
in
synthesis.
The
specific
chemistry
and
applications
of
a
hexahydrate
depend
on
the
identity
of
the
non-water
component
and
the
overall
crystal
structure.