Qualitative Analysis
Detection of carbon and
hydrogen
Detection of N. S and X(Cl,
Br an I)
[Lassaigne’s Test (Sodium
extract)]
 Detection of N
C, H (Organic Compound) + CuO
CO2 + H2O
Ca(OH)2 + CO2  CaCO3 (Lime water turns milky)
Anhydrous CuSO4 + 5 H2O  CuSO4.5H2O (Blue)
Organic compound is converted to inorganic compound (by fusing with Na) because inorganic
reactions are faster than organic reactions.
C, H N (Organic Compound) + Na
C, H, S + Na
Na2 S
C, H , N, S + Na
6NaCN
(Sodium Extract)
+
NaCN
NaSCN
Fe(OH)2
(Ferrous Hydroxide)

Na4[Fe(CN)4]
+ 2 NaOH
Fe2(SO4)3
Fe4[Fe(CN)4]3
(Ferric Ferrocyanide)
 Detection of S
 Detection of NaCNS
 Test for X
Colour:- Prussian Blue
PbS 2CH3COONa
(Black ppt.)
Na3[Fe (NOS)(CN)5]
(Sodium thionitroprusside)
(purple)
NaCNS
+
FeCL3

Fe(CNS)3
+
3 NaCl
(Blood Red Colour)
Before the test. Sodium extract is boiled with HNO3 to remove interfering radicals [ Cn- and H2as HCN and H2S gas]
NaCl + AgNO3  AgCl (White ppt.)
Na2S
+
(Sodium Sulphide)
Na2S
+
(Ch3COO)2Pb

(Lead Acetate)
Na2[Fe(NO)(CN)5]

(Sodium nitroprusside)
NaBr + AgNO3  AgBr (Pale yellow ppt.)
NaI + AgNo3 –AgI (Yellow ppt.)
 Test For P
If Ammonium Chloride is added,
AgCl  Completely Dissolves
AgBr  Partially dissolves
AgI  Does not dissolve in NH4Cl
C, H , P
+ Na2O2
(Organic compound with
Phosphorous)
HNO3
Na3PO4
H3PO4
+
(NH4)2MoO4
(Ammonium
Molybdate)
(NH4)3PMo12O40 [Yellow ppt.]
(Ammonium Phosphomolybdate)