Analytical ChemistryHard
Question
H2S in the presence of HCl precipitates II group but not IV group because :
Options
A.HCl activates H2S
B.HCl increases concentration of Cl-
C.HCl decreases concentration of S2-
D.HCl lowers the solubility of H2S in solution
Solution
H2S ⇋ 2H+ + S2- ; HCl ⇋ H2+ + Cl-.
Due to common ion effect, the ionisation of H2S is suppressed and thus low concentration of S2- ions is obtained. This much of S2- ions concentration is enough to precipitate only IInd group cations (because of the low KSP of IInd group sulphides).
Due to common ion effect, the ionisation of H2S is suppressed and thus low concentration of S2- ions is obtained. This much of S2- ions concentration is enough to precipitate only IInd group cations (because of the low KSP of IInd group sulphides).
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