Sciencemadness Discussion Board

Are metal ammine complexes unstable in concentated sodium hydroxide solution?

Foeskes - 13-10-2017 at 21:50

I'm going to precipitate separate nickel and chromium from iron by complexity them with ammonia and precipitate the iron ad Fe(OH)2. But I have to convert them both to the hydroxide to separate the two of them. So will sodium hydroxide destroy the complexes or do I have to use another route?

DraconicAcid - 14-10-2017 at 00:16

Concentrated sodium hydroxide should destroy the complexes, yes. The nickel one particularly.

wg48 - 14-10-2017 at 02:04

Some alkali (for example ph10) formulations of electro less nickel use ammonia to complex the nickel and prevent the precipitation of the hydroxide. So if iron hydroxide is precipitated at that ph significant separation will be achieved. How easily the iron hydroxide can be filtered out is an other problem.

DraconicAcid - 14-10-2017 at 08:11

I know that dry [Ni(NH3)6]Cl2 will readily lose ammonia at room temperature- if you heat a concentrated solution of the ammonia complex, especially if there's high concentrations of hydroxide, you'll probably boil off the ammonia.