Home
Class 12
CHEMISTRY
H(2)S in the presence of HCl precipitate...

`H_(2)S` in the presence of `HCl` precipitates `II` group but not `IV` group because:

A

`HCl` activates `H_(2)S`

B

`HCl` increase concentration of `Cl^(-)`

C

`HCl` decreases concentration of `S^(2-)`

D

`HCl` lowers the solubility of `H_(2)S` in solution.

Text Solution

Verified by Experts

The correct Answer is:
C
`H_(2)S hArr2H^(+)+S^(2-),HClhArrH_(2)^(+) +Cl^(-)`
Due to common ion effect, the ionisation of `H_(2)S` is suppressed and thus low concentration of `S^(2-)` ions is obtained This much of `S^(2-)` ions concentration is enough to precipitate only `II^(nd)` group cations (because of the low `K_(SP)` of `II^(nd)` group sulphides)
Promotional Banner

Similar Questions

Explore conceptually related problems

Mg is not precipitated in V group because:

In equalitative analysis, cations of graph II as well as group IV both are precipitated in the form of sulphides. Due to low value of K_(sp) of group II sulphides, group reagent is H_(2)S in the presence of dil. HC1 , and due to high value of K_(sp) of group IV sulphides, group reagent is H_(2)S in the presence of NH_(4)OH and NH_(4)C1 . In a solution containing 0.1M each of Sn^(2+), Cd^(2+) , and Ni^(2+) ions, H_(2)S gas is passed. K_(sp) of SnS = 8 xx 10^(-29), K_(sp) of CdS = 15 10^(-28), K_(sp) of NiS - 3 xx 10^(-21), K_(1) of H_(2)S = 1 xx 10^(-7), K_(2) of H_(2)S = 1 xx 10^(-14) At what value of pH, NiS will start to precipitate?