1. INORGANIC PRESENTATION
TOPIC: THEORITICAL ASPECTS OF
ANIONS
SUBMITTED BY: NIDHI CHAUDHARY
B.Sc(H) CHEMISTRY
VI SEMESTER

2. QUALITATIVE
INORGANIC
ANALYSIS
It is the analysis (i.e. detection and
identification) of the cations and
anions present in given compound
or salt mixture.

3. IDENTIFICATION OF ANIONS
AND CATIONS
Identification of anions/cations is done through
a series of tests, broadly divided into :
 Preliminary tests : provide us with the idea of
the cation/anion present in the compound.
 Confirmatory tests : confirm the presence of the
cation/anion in a given compound.

4. ANIONS
 Anion is an ion with more electrons than
protons, giving it a net negative
charge (since electrons are negatively
charged and protons are positively
charged).
 Anions are contributed by acids, therefore,
they are called as acid radicals.
For example, the anion (or acid radical) Cl-
in a water solution of salt sodium chloride
(NaCl) comes from the hydrochloric acid
(HCl) and the cation (or basic radical) Na+
from the base sodium hydroxide (NaOH).

5. PREPARING TEST
SOLUTIONS
Most of the confirmatory tests of the cations/anions are not
carried out with the solid mixture but with their solutions :
 Water Extract: If the given compound is soluble in water,
then 1-2 g of mixture is dissolved in distilled water (10-20
ml).
 Sodium Carbonate (soda) Extract: If the compound is
insoluble in water, then 1 g of mixture is taken along with
2 g Na2CO3 in distilled water (15-20 ml) and heated for
15 minutes. Solution is filtered and the filterate is soda
extract.

6. CLASSIFICATION OF ANIONS
Anions can not be classified into specific
groups but their action with sulphuric
acid divides them into three
categories:
 Dilute Sulphuric Acid: CO 2-, NO -,
3 2
CH3COO-, S2-, SO32-
 Conc. Sulphuric Acid: Cl-, Br-, I-, NO -,
3
 Independent Radicals: SO 2-,PO 3-,BO 3-,
4 4 3
C2O42-

7. SNo EXPERIMENT OBSERVATIONS INFERENCE
1. TEST FOR CARBONATE
(CO32-)
Pre. Test : To a pinch of Colorless gas evolves May be CO32- .
mixture add few drops of with brisk
dilute sulphuric acid. effervescence.
2 H+ + CO32- H2O +
CO2
Con. Test : Pass the gas Lime water turns
evolved in the above step milky.
through lime water. M(OH)2 + CO2 MCO3 CO32-
+ H2O confirmed.

8. SNo. EXPERIMENT OBSERVATIONS INFERENCE
2. TEST FOR NITRITE
(NO2-) Reddish brown vapors
Pre. Test : To a pinch of observed. May be NO2- .
mixture in test tube, add dilute 2MNO2 + H2SO4 M2SO4
sulfuric acid. + HNO2
3MNO2 H20 + HNO3 +
NO
NO + O2 NO2 (brown
fumes)
Con. Test : (a) To the above A deep blue coloration
solution, add 0.5 ml of observed.
potassium iodide solution NO2- confirmed.
2KI + 2MNO2 + H2SO4
followed by 0.5 ml of pure K2SO4 + I2 + NO + H2O
starch solution.
I2 + STARCH BLUE
COLORED COMPLEX
(b) Take water extract or soda
extract of the compound and A dark brown or black
coloration obtained. NO2- confirmed.
add dilute sulfuric acid
followed by freshly prepared MNO2 + H2SO4 MSO4 +
ferrous sulphate solution. HNO2
HNO2 HNO3 + NO
FeSO4 + NO FeSO4.NO

9. SNo. EXPERIMENT OBSERVATIONS INFERENCE
3. TEST FOR ACETATE
(CH3COO-)
Pre. Test : A pinch of mixture Vinegar like smell is May be CH3COO- .
is treated with dilute sulphuric obtained.
acid . M(CH3COO) + H2SO4
CH3COOH + MSO4
OR,
1-1.5 g of mixture is taken in Vinegar like smell is
watch glass to which a pinch obtained.
of oxalic acid and a few drops
of water were added.
Deep red colored
Con. Test: (a) 1 ml of precipitate is observed
water/soda extract is due to formation of a
neutralized with dilute acetic complex.
acid followed by addition of
ferric chloride solution. CH3COO- + Fe3+ + H2O CH3COO- confirmed.
[Fe3(OH)2(CH3COO)6]+ +
2H+
[Fe3(OH)2(CH3COO)6]+ +
H2O CH3COOH +
[Fe(OH)2(CH3COO)] + H+

10. SNo. EXPERIMENT OBSERVATIONS INFERENCE
(b) To 1 ml of water/soda CH3COO- confirmed.
Blue color is obtained.
extract lithium nitrate
solution and potassium
iodide solution were added.
After this, few drops of
dilute ammonia solution was
added and the resultant
solution was heated.
(c) Equal volume of soda/water
CH3COO- confirmed.
extract and pure calcium Yellow precipitate is
hydroxide is taken in a test obtained.
tube. Heat the solution and Ca(OH)2 + M(CH3COO)
pass the evolved vapors into CH3COCH3
a solution of 2,4 DNP
hydrazine. CH3COCH3 +
H2NHC6H5(NO2)
(CH3)2CNNHC6H5(NH2)2

11. SNo. EXPERIMENT OBSERVATIONS INFERENCE
4. TEST FOR SULPHIDE
(S2-)
Pre. Test: Take a pinch of A colorless gas evolves May be S2- .
mixture in a test tube and which smells like rotten
add dilute sulphuric acid. egg.
S2- + H2SO4 H2S + SO42-
Con Test: a) Pass the above Yellow precipitate is
gas in cadmium acetate. obtained.
Cd(CH3COO)2 + H2S CdS
S2- confirmed.
+ CH3COOH
Acidify 1-2 ml of soda/water Black precipitate obtained.
(b) extract with dilute acetic H2S + Pb(CH3COO)2 PbS
acid and boil the solution to + CH3COOH
expel carbon dioxide. To this S2- confirmed.
add 1-2 ml of lead acetate
solution.
Add 1-2 ml of freshly
(c) prepared sodium Violet coloration obtained.
nitroprusside solution to the S2- + Na2[Fe(CN)5NO]
soda/water extract. S2- confirmed.
Na4[Fe(CN)5NOS]

12. SNO EXPERIMENT OBSERVATIONS INFERENCE
5. TEST FOR SULPHITE
(SO32-)
Pre. Test: Take a pinch of A colorless and pungent May be SO32-
mixture and add 2-3 ml of smelling gas evolves.
dilute sulphuric acid.
Con.Test: (a) Take 1-2 ml of A green color is obtained.
soda/water extract; add 2-3 3Na2SO3 + K2Cr2O7 + 4H2SO4
ml of dilute sulphuric acid Cr2(SO4)3 (Green color)
and few drops of potassium SO32- confirmed.
dichromate solution. + 3Na2SO4 + 4H2O + K2SO4
(b) Take a pinch of mixture and Sulphur dioxide is evolved.
add 2-3 ml of dilute
hydrochloric acid. SO32- confirmed.
White precipitate is
Pass the gas evolved obtained.
through lime water.

13. SNo EXPERIMENT OBSERVATIONS INFERENCE
6. TEST FOR CHLORIDE
(Cl-)
Pre Test: To a pinch of Greenish yellow gas having May be Cl- .
mixture, add 1-2 ml of conc. pungent smell evolves.
sulphuric acid. Dense white fumes observed.
Bring a glass rod dipped in NaCl + H2SO4 NaHSO4 +
ammonium hydroxide near HCl
the mouth of the above test
HCl + NH4OH NH4Cl + H2O
tube.
White precipitate formed
Con. Test: (a) To the which is soluble in excess of
water/soda extract, add dilute ammonium hydroxide.
nitric acid and few drops of AgNO3 + NaCl AgCl +
silver nitrate. NaNO3
Cl- confirmed.
AgCl + 2NH4OH
[Ag(NH3)2Cl] (soluble
complex) + 2H2O

14. SNO EXPERIMENT OBSERVATIONS INFERENCE
(b) Chromyl Chloride Test - Yellow precipitate is formed. Cl- confirmed.
Take about 0.2 g of mixture K2Cr2O7 + 4NaCl + 6H2SO4
in a test tube and add about 2CrO2Cl2
0.3 g of solid potassium (chromyl chloride) + 2KHSO4
dichromate and 2 ml of + 4NaHSO4 + 3H2O
conc. sulphuric acid. Heat
the mixture and pass the gas
evolved into a tube CrO2Cl2 + 4NaOH
containing sodium Na2CrO4 + 2NaCl + 2H2O
hydroxide solution. Add 1 ml
of lead acetate solution.
Na2CrO4 + Pb(CH3COO)2
PbCrO4 (yellow) +
2CH3COONa

15. SNO EXPERIMENT OBSERVATIONS INFERENCE
7. TEST FOR BROMIDE
(Br-)
Pre. Test: To a pinch of Reddish brown vapors
mixture, add conc. with a pungent smell May be Br-.
sulphuric acid. evolved.
KBr + H2SO4 KHSO4 +
HBr
2HBr + H2SO4 Br2 + SO2
+ 2H2O
Con Test: (a) Take 0.5 ml of
soda/water extract and Yellow precipitate obtained
then add 0.5 ml of dilute which is sparingly soluble
nitric acid and few drops of in ammonium hydroxide.
silver nitrate solution. NaBr + AgNO3 AgBr Br- confirmed.
+ NaNO3
AgBr + 2NH4OH
[Ag(NH3)2]Br + 2H2O

16. SNO EXPERIMENT OBSERVATIONS INFERENCE
(b) Take 0.5 ml of soda/water Organic solvent layer Br- confirmed.
extract of the mixture and attains orange color due to
add 0.5 ml of carbon dissolution of evolved
tetrachloride or chloroform bromine in it.
followed by 1 ml of conc. NaBr + HNO3 NaNO3 +
nitric acid or chlorine HBr
water. Warm the mixture
and shake the test tube. 2HBr + 2HNO3 Br2 +
2NO2 + 2H2O

17. SNO EXPERIMENT OBSERVATIONS INFERENCE
8. TEST FOR IODIDE
(I-)
Pre. Test: To a pinch of Violet vapors of iodine May be I-.
mixture, add conc sulphuric evolved due to partial
acid. decomposition of the
formed HI.
KI + H2SO4 KHSO4 +
HI
2HI + H2SO4 I2 + SO2 +
2H2O
Con Test: (a) Take 0.5 ml of
soda/water extract and then Yellow precipitate
add 0.5 ml of dilute nitric obtained which is
acid followed by 0.5 ml of insoluble in ammonium I- confirmed.
silver nitrate solution. hydroxide.
NaI + AgNO3 AgI +
NaNO3

18. SNO EXPERIMENT OBSERVATIONS INFERENCE
(b) Take 0.5 ml of soda/water Organic solvent layer I- confirmed.
extract of the mixture and attains violet color
add 0.5 ml of carbon due to dissolution of
tetrachloride or chloroform iodine in it.
followed by 1 ml of conc. NaI + HNO3 NaNO3 +
Nitric acid or chlorine water. HI
Warm the mixture and shake
the test tube vigorously. 4HI + O2 2I2 + 2H2O

19. SNO EXPERIMENT OBSERVATIONS INFERENCE
9. TEST FOR NITRATE
(NO3-)
Pre. Test: To a pinch of Light brown fumes May be NO3-
mixture, add conc sulphuric observed which intensify
acid. on heating the mixture
with copper turnings.
NaNO3 + H2SO4
NaHSO4 + HNO3
4HNO3 4NO2 + O2 +
2H2O
Con Test: Take around 1 ml A brown black ring at the
of soda/water extract and junction of two layers is
acidify with dilute sulphuric formed.
acid. Add 2-3 ml of freshly NaNO3 + H2SO4 NO3- confirmed.
prepared ferrous sulphate NaHSO4 + HNO3
solution and then pour
2HNO3 + 6FeSO4 + 3H2SO4
conc. sulphuric acid slowly
in thin stream along the 3Fe2(SO4)3 + 2NO +
sides of the test tube. 4H2O
FeSO4 + NO
FeSO4.NO(brown ring)

20. SNO EXPERIMENT OBSERVATIONS INFERENCE
10. TEST FOR OXALATE
(C2O42-)
Pre. Test: Add conc Evolved gas burns with a May be C2O42-.
sulphuric acid(1-2 ml) to a blue flame.
pinch of given mixture(0.1 g) (COONa)2 + H2SO4
and heat the solution. . Na2SO4 + (COOH)2
Bring the mouth of the test (COOH)2 CO + CO2 +
H2O
tube near the flame.
Also pass the gas in the lime
water. Lime water turns milky.
Con Test: (a) Acidify 1 ml of
soda/water extract of the White precipitate obtained.
mixture with dilute acetic (COONa)2 + H2SO4
acid and boil the solution. Na2SO4 + (COOH)2
Then add 1 ml of calcium
chloride solution and shake (COOH)2 + CaCl2
the test tube. (COO)2Ca + 2HCl

21. SNO EXPERIMENT OBSERVATIONS INFERENCE
Dissolve the precipitate in Pink color of potassium C2O42- confirmed.
permanganate gets
minimum quantity of dilute
discharged.
sulphuric acid and then add
potassium permanganate (COO)2Ca + H2SO4
solution drop wise. (COOH)2 + CaSO4
2KMnO4 + 3H2SO4 +
5(COOH)2 2MnSO4 +
K2SO4 + 10CO2 + 8H2O
(b) Acidify soda/water extract
with dilute acetic acid and Yellow precipitate
boil the solution. Add ferrous obtained.
sulphate solution. C2O42- confirmed.
C2O42- + Fe2+
[Fe(C2O4)]2-

22. SNO EXPERIMENT OBSERVATIONS INFERENCE
11. TEST FOR FLUORIDE
(F-)
Pre. Test: Take 0.1 g of the Oily droplets are formed May be F-
mixture and add 1 ml of along the sides of the test
tube.
conc. sulphuric acid.
2NaF + H2SO4 Na2SO4 +
2HF
Con Test: Add a pinch of White gelatinous deposit
sand to the above reaction on the glass rod observed.
mixture. Heat it. Bring a F- confirmed.
4NaF + H2SO4 + SiO2
glass rod moistened with
water near the mouth of SiF4 + 2Na2SO4 + 2H2O
the test tube. 3SiF4 + 4H2O H4SiO4 +
2H2SiF6 (hydrofluorosilicic
acid; waxy appearance)

23. SNO EXPERIMENT OBSERVATIONS INFERENCE
12. TEST FOR SULPHATE
(SO42-)
To the soda/water extract (1 White precipitate obtained SO42- confirmed.
ml) add dilute hydrochloric which is insoluble in conc
acid (1 ml) so as to remove hydrochloric acid.
the carbonate (if present). Na2SO4 + BaCl2 BaSO4
Add 1 ml of barium chloride + 2NaCl
solution.
13. TEST FOR PHOSPHATE
(PO43-)
Take a pinch of the given PO43- confirmed.
mixture in a test tube and add
Yellow precipitate is
about 1 ml of conc nitric acid.
obtained.
Boil the contents and add
excess of ammonium PO43- + 12MoO42- + 24H+
molybdate solution. PMo12O403- + 12H2O

24. SNO EXPERIMENT OBSERVATIONS INFERENCE
14. TEST FOR BORATE
(BO33-)
In a porcelain dish, take a Green flame is observed. BO33- confirmed.
small amount of the mixture, Na3BO3 + 3H2SO4
say 0.2-0.3 g, and add nearly Na2SO4 + 2H3BO3
1 ml of conc sulphuric acid
followed by 1 ml of ethyl
alcohol. Heat the dish and H3BO3 + C2H5OH
bring a burning paper over B(OC2H5)3 + H2O
it.