What is the group reagent of group 3 cations?
Answers
Answer:
The group reagent is ammonium hydroxide in the presence of ammonium chloride
Answer:
The group reagent is ammonium hydroxide in the presence of ammonium chloride.
Explanation:
In qualitative analysis, III
rd
group includes Fe
3+
,Al
3+
and Cr
3+
. The group reagent is ammonium hydroxide in the presence of ammonium chloride. NH
4
CI is added to suppress the ionisation of NH
4
OH so that only the III
rd
group radicals are precipitated as their insoluble hydroxide and not the IV
th
and V
th
group radicals as the solubility products of their hydroxides are much higher. Before adding group reagent to the filtrate of IInd group, one drop of concentrated HNO
3
(oxidising agent) is added and the content is boiled for 2-3 minutes and then cool because the solubility product of Fe(OH)
2
is very high as compared to Fe(OH)
3
. When a light bluish-green crystalline double salt-containing cations of III
rd
group and zero groups are analysed. it responds to the following tests/reactions.
(a) Its aqueous solution gives a reddish-brown precipitate with an alkaline solution of potassium tetraiodomercurate (II)
(b) Its aqueous solution after boiling with conc. HNO
3
gives a reddish-brown precipitate with sodium hydroxide.
(c) The solution of reddish-brown precipitate in oil.HCI gives blood red colouration with ammonium sulphocyanide and Prussian blue with potassium ferrocyanide.
(d) It's a very dilute solution gives a white precipitate with (CH
3
COO)
2
Pb solution and a white precipitate are only soluble in hot ammonium acetate