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Step
1:Â Obtain
the
inorganic
salt
whose
cation
and
anion
you
must
identify.
Step
2:Â Conduct
preliminary
tests
for
the
anion
group-wise
until
you
obtain
a
positive
result.
Anions
and
cations
are
classified
into
groups
that
share
the
same
group
reagent
and
therefore,
have
similar
preliminary
tests.
Step
3:Â Once
you
get
a
positive
result
for
a
preliminary
test
for
an
anion,
conduct
a
confirmatory
test
for
that
anion.
(If
you
get
a
positive
result,
move
on
to
step
4.
If
you
don’t,
go
back
to
conducting
preliminary
tests
for
anions.)
Step
4:Â Conduct
preliminary
tests
for
cations
group-wise
until
you
obtain
a
positive
result.
Step
5:Â Once
a
positive
result
is
obtained,
conduct
a
confirmatory
test
for
that
cation.
Step
6:Â Now
that
the
cation
and
the
anion
are
identified,
obtain
the
chemical
formula
of
the
salt
by
balancing
the
charges
of
the
cation
and
anion.
For
example,
if
your
cation
is
Fe3+Â and
your
anion
is
Cl–,
the
chemical
formula
of
the
salt
will
be
FeCl3.
Note:Â You
can
also
identify
the
cation
first
and
then
move
on
to
identifying
the
anion.
Salt
Analysis
Answer
Format
(Sample)
A
sample
answer
format
for
salt
analysis
is
provided
below.
Aim:Â To
identify
the
acidic
radical
and
the
basic
radical
of
the
given
inorganic
salt.
Apparatus
Required:Â Fill
as
per
requirement.
Procedure:
(i)
Preliminary
Test
for
Anion:
ExperimentObservationInference
(ii)
Confirmatory
Test
for
Anion:
ExperimentObservationInference
(iii)
Preliminary
Test
for
Cation:
ExperimentObservationInference
(iv)
Confirmatory
Test
for
Cation:
ExperimentObservationInference
Result:Â The
acidic
radical
is (anion),
and
the
basic
radical
is (cation).
Therefore,
the
given
salt
is
identified
to
be (salt).
Tricks
and
Shortcuts
for
Salt
Analysis
Always
check
the
colour
of
the
salt
first.
Certain
cations
have
coloured
salts.
If
the
salt
is
coloured,
you
can
directly
conduct
a
preliminary
test
for
the
cation
that
forms
salts
of
that
colour.
The
cations
that
form
coloured
salts
are
tabulated
below:
Colour
of
the
Inorganic
SaltCationBlueCu2+Deep
blueCo2+Â (anhydrous
salt)Greenish-blueCu2+Â (hydrated
salt)GreenNi2+Â (hydrated
salt)Light
greenFe2+Yellow,
brown,
or
yellowish-brownFe3+Pale
pinkMn2+Rose-redCo2+Â or
mercuric
iodide
(HgI2)Purple
or
dark
greenCr3+
If
the
salt
is
colourless,
perform
a
flame
test
first
(since
the
presence
of
3
different
cations
can
be
confirmed
by
it).
An
easier
way
to
perform
the
flame
test
is
to
pick
up
a
chunk
of
the
salt
with
test
tube
holders,
pour
a
few
drops
of
concentrated
HCl
on
it,
and
expose
it
to
the
flame
of
a
Bunsen
burner.
If
you
do
not
gain
any
insight
into
the
cation
from
the
flame
test
(or
from
visual
inspection),
proceed
with
group-wise
preliminary
tests
for
cations.
Note
that
some
cations
do
not
form
salts
with
certain
anions,
as
listed
below.
Ba2+,
Sr2+,
Pb2+,
and
Ca2+Â do
not
form
salts
with
the
sulphate
anion
(SO42-).
Only
group
0,
group
1,
and
group
2
cations
form
salts
with
the
phosphate
anion
(PO43-).
If
you
identify
one
of
these
cations
in
the
salt
analysis,
you
need
not
conduct
tests
for
the
corresponding
anions.
Finally,
certain
salts
are
very
common
in
salt
analysis
examinations.
For
example,
the
most
common
salt
containing
the
bromide
ion
(Br–)
is
NH4Br
and
the
most
common
salt
containing
the
calcium
cation
(Ca2+)
is
CaCl2.
Also,
some
salts
can
be
identified
by
observing
their
texture
and
appearance
(for
example,
calcium
carbonate
has
the
texture
of
powdered
chalk).
Therefore,
visiting
your
chemistry
laboratory
and
physically
examining
the
salts
may
help
you
quickly
analyze
the
salt
in
the
practical
examination.
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