What is yellow ammonium sulphide? Why is yellow ammonium sulphide and not ordinary ammonium sulphide used for the separation of $$IIA$$ and $$IIB$$ sub-group?
Ammonium sulphate aqueous solution is a colourless to yellow liquid, with an odour of rotten eggs or ammonia. Yellow ammonium sulphide is really a mixture of ammonium polysulphides and is made by dissolving sulphur in colourless $$NH_{4}HS/NH_{3}$$.
Yellow ammonium sulphate is a suitable reagent for the separation of CdS (II A ) and $$As_{2}O_{3}$$(II B). It is used for the separation of group II-A and group II B sulphides. Group II A sulphides are insoluble in water whereas group II B sulphides are soluble in yellow ammonium sulphate.