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The ion that cannot be precipitated by both HCl and H2S is
Sn2+ can be precipitated by H2S as chocolate colored precipitate SnS but not by HCl.
Which one among the following pairs of ions cannot be separated by H2S in dilute hydrochloric acid? (1986 - 1 Mark)
NOTE : The ions of group II of salt analysis are precipitated by HCl and H2S whereas members of group IV are precipitated by H2S in alkaline medium.
∵ Bi3+ and Sn4+ both belong to group II
∴ They will be precipitated by HCl in presence of H2S. Both Bi3+ and Sn4+ belong to group II of qualitativeinorganic analysis and will get precipitated by H2S.
An aqueous solution contains Hg2+, Hg22+, Pb2+ and Cd2+.The addition of HCl (6N) will precipitate : (1995S)
NOTE : Only group I cations are precipitated by dil. HCl
Only PbCl2 and Hg2Cl2 will precipitate as Pb2+ and Hg22+ as first group basic radicals and their solubility product is less than the other radicals.
NOTE : dil. HCl is the first group reagent.
Identify the correct order of solubility of Na2S, CuS and ZnS in aqueous medium (2002S)
Sodium salts are highly soluble. Cu2+ belongs to the IInd group in salt analysis and is precipitated as CuS, whereas Zn2+ belongs to the IV group and is precipitated as ZnS after CuS because of higher Ksp of ZnS.
An aqueous solution of a substance gives a white precipitate on treatment with dilute hydrochloric acid, which dissolves on heating. When hydrogen sulfide is passed through the hot acidic solution, a black precipitate is obtained. The substance is a (2002S)
A gas 'X' is passed th rough water to form a satur ated solution. The aqueous solution on treatment with silver nitrate gives a white precipitate. The saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas 'Y'. Identify 'X' and 'Y'. (2002S)
Since the saturated aqueous solution of (X) give white ppt with AgNO3, so (X) may be Cl2. Hence
[X] + H2SO4 —→ [Y] a colourless gas with irritating smell, [Y] + K2Cr2O7 + H2SO4 —→ green solution. [X] and [Y] are:(2003S)
SO2 and H2S, both being reducing agents, can turn acidified dichromate solution green. SO2 can be obtained by the action of acid upon sulphite, while H2S is evolved by the action of acid upon sulphide.
However, SO2 has a burning sulphur smell which is irritating. H2S has rotten egg like smell.
A solution which is 10-3 M each in Mn2+, Fe2+, Zn2+ and Hg2+ is treated with 10-16 M sulphide ion. If Ksp of MnS, FeS, ZnS and HgS are 10-15, 10-23, 10-20 and 10-54 respectively, which one will precipitate first? (2003S)
TIPS/Formulae : For precipitation, Ionic product > solubility product HgS having the lowest Ksp among the given compounds will precipitate first.
A metal nitrate reacts with KI to give a black precipitate which on addition of excess of KI is converted into orange colour solution. The cation of the metal nitrate is (2005S)
The metal ion is Bi3+.
A solution when diluted with H2O and boiled, gives a white precipitate. On addition of excess NH4Cl/NH4OH, the volume of precipitate decreases leaving behind a white gelatinous precipitate. Identify the precipitate which disolves in NH4OH/NH4Cl (2006 - 3M, –1)
Precipitate of Zn(OH)2 formed at initial stage dissolves in excess of NH4OH due to the formation of tetrammine Zn (II) complex.
A solution of a metal ion when treated with KI gives a red precipitate which dissolves in excess KI to give a colourless solution. Moreover, the solution of metal ion on treatment with a solution of cobalt (II) thiocyanate gives rise to a deep blue crystalline precipitate. The metal ion is (2007)
Passing H2S gas into a mixture of Mn2+, Ni2+, Cu2+ and Hg2+ ions in an acidified aqueous solution precipitates (2011)
In presence of acid, ionisation of H2S is supressed, so less number of S2– are furnished. Hence only those sulphides are precipitated which has low solubility product (Ksp); thus only CuS and HgS are precipitated.
Upon treatment with ammoniacal H2S, the metalion that precipitates as a sulfide is (JEE Adv. 2013)
The group reagent of fourth group is ammoniacal H2S by which Zn2+ ion will be precipitated as ZnS, whereas Fe3+ ion and Al3+ ions will be precipitated as hydroxides.
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