Question

A solution may contain any of the Group III cations. Treatment of the solution with ClO- in alkaline medium yields a yellow solution and a colored precipitate. The acidified solution is unaffected by treatment with NH3. The colored precipitate dissolves in nitric acid; addition of excess NH3 to this acidic solution produces only a blue solution. On the basis of this information, which Group III cations are present, absent, or still in doubt.

Presnet ________

Abesent ________

In Doubt _______

Answer 1

For group III cation, we have in their hydroxide ppt form.

On treatment with ClO- in basic medium gives CrO4 2- and Al(OH)4 - in solution and color of CrO4 2- is yellow.

The color ppt dissolve in HNO3 and treatment with NH3 in acidic medium give blue color solution. Ni(OH)2 dissolve in HNO3 and with NH3 give [Ni(NH3)6]2+ which is in blue color.

Present ________ Ni2+ and Cr3+

Abesent ________ Al3+ and Fe3+

In Doubt _______ Nil