EXP 27

Qualitative analysis-

- Process for determining which element/ion is present in a sample “Wet analysis” is useful in finding chemical equilibrium, solubility properties, and characteristic redox reactions for ions

Group 1 Cations

Ag +1 , Hg2 2+, Pb 2+ = Acid insoluble chlorides

When dilute HCl is added to , the Group 1 cations form soluble chloride precipitates

Ag+1 presence is confirmed by the reprecipitation of AgCl (white) Hg2 +2 presence is confirmed by the formation of a gray-black precipitate Pb+2 presence is confirmed by the formation of PbCrO4 (yellow)

Ksp

Ksp (solubility product constant) measures relative solubility of particular species

For precipitation to occur, Q (ion product) must exceed the Ksp value, so Q>Ksp

Ksp Group 1 Values

Ksp= [Ag+1 ][Cl-1 ] …. 1.8 x 10-10

Ksp= [Hg2 +2 ][Cl-1 ]2 …1.3 x 10-18

Ksp= [Pb+2 ][Cl-1 ]2….1.6 x 10-5