Single Choice

In $$IV$$ group analysis, $$NH_{4}OH$$ is added before passing $$H_{2}S$$ gas because:

Athe sulphides of $$IV$$ group are insoluble in $$NH_{4}OH$$
Bthe sulphides of other metals are soluble in $$NH_{4}OH$$
Cthe concentration of $$S^{2-}$$ ions is high enough precipitate the sulphides of $$IV$$ group
Correct Answer
Dthe sulphides of second group are soluble in $$NH_{4}OH$$

Solution

Solubility product of sulphides of group (II) radicals are less than solubility product of sulphides of (IV) group. So to precipitate (II) group radicals as sulphides $$S^{2-}$$ are sufficient. In presence of Dil $$HCl$$ $$S^{2-}$$ are released due to the common ion effects. In (IV) group the ionisation of $$H_2S$$ is favoured by the use of $$NH_4OH$$

Hence option (C) is correct.

SIMILAR QUESTIONS

Chemistry Practical

The cation that will not be precipitated by $$H$$_2S$$ in the presence of dil $$HCl$$ is:

Chemistry Practical

A solution containing a group-IV cation gives a precipitate on passing $$H_2S$$. A solution of this precipitate in $$dil.HCl$$ produces a white precipitate with basic $$NaOH$$ solution and bluish-white precipitate with basic potassium ferrocyanide. The cation is:

Chemistry Practical

In Nessler's reagent for the detection of ammonia the active species is:

Chemistry Practical

A reddish-pink substance on.heating gives off a vapor which condenses on the sides of the test tube and the substance turns blue. If on cooling water is added to the residue, it turns to its original color. The substance is :

Chemistry Practical

Reagent used in the qualitative analysis of IVth group is

Chemistry Practical

Group reagent for analytic group $$IV$$ is

Chemistry Practical

Precipitate of group $$IV$$ cations takes place when $$H_2S$$ is

Chemistry Practical

Mark the correct statement(s)

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