Page 68 - Chemistry - XI

Cu OH +2NH NO +2NH OH Cu NH NO +4HO

3 4
4
2
2
3
4
3 2
Deep blue complex

Soluble

KFeCN test:
2.
4
6

Cu NH NO +4CH COOOH Cu NO +4CH COONH 4

3 4
3
3
3 2
3 2

2CuNO + KKFeCN Cu FeCN + 4KNO

3 2 4 6 2 6 3
Choclate brown ppt.

FLOW CHART FOR ANALYSIS OF GROUP - II
Filtrate of Group I
Pass H S gas
2
Precipitate No precipitate
Group II present Group II absent
Filter
Proceed for
Black ppt. analysis of
Group III to VI
Heat with 50% HNO 3

Colourless solution Bluish green
solution
Boil off H S gas, cool
2
and divide into two parts Boil off H S and divide the
2
solution into two parts

KI solution K CrO 4 NH OH KFeCN

2

4
solution solution 4 6
Yellow Chrome yellow Deep blue Chocolate brown
precipitate precipitate which solution precipitate
dissolves in
NaOH solution

Cu confi rmed
+2
Pb confi rmed
+2
GROUP - III (Fe , Al )
+3
+3
If fi rst and second groups are absent, proceed with 5 mL of original solution directly. But if any of these groups fi rst and second groups are absent, proceed with 5 mL of original solution directly. But if any of these groups
If
is present, we shall begin with the fi
is present, we shall begin with the fi ltrate of the corresponding group. ltrate of the corresponding group.
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