चयनात्मक अवक्षेपण (selective precipitation) पर सिद्धान्त बताइए ।

What is the principle of selective precipitations ?

Mg^(2+) ions is essential for selective precipitation of Fe(OH)_(3) by aqueous NH_(3) .

The addition of ammonium chloride to a solution containing ferric and magnesium ions is essential for selective precipitation of ferric hydroxide by aqueous ammonia.

Selective precipitation of ions in a mixture in the form of salts can be adding common ions gradually. Let us condsider selective precipitation of CI^(-) and CrO_(4)^(2-) ions in the form of AgCl and Ag_(2)Cro_(4) form a mixture having having 0.01M CI^(-) and 0.01M CrO_(4)^(2-) . For this, salt having Ag^(+) [like AgNO_(3)(s) ] is added gradually. Given : K_(sp) [AgCI]=10^(-10) and K_(sp)[Ag_(2)CrO_(4)]=4xx10^(-14)] The percentage of one ion precipitated when another ion starts precipitation is : (Given: (1)/(sqrt2)=0.7 )

condition for precipitation(ionic product),comparison OF solubilities, selective precipitation, application OF common ion effect in qualitative analysis

The reagment (s) that can selectively precipitate S^(2-) from a mixture of S^(2-) and SO_(4)^(2-) in aqueous solution is (are)