Precipitation Reactions with sodium hydroxide and ammonia

• [Cu(H2O)6 ]2+

  blue solution makes blue ppt

  
• [Mn(H2O)6 ]2+ (aq)

  very pale pink solution makes pale brown ppt

  
• [Fe(H2O)6 ]2+ (aq)

  green solution makes green ppt

  
• [Fe(H2O)6 ]3+ (aq)

  yellow/brown solution makes brown ppt

  
• [Cr(H2O)6 ]3+ (aq)

  green solution makes green ppt

  
• With ammonia when added in limited amounts the same hydroxide precipitates form. The ammonia acts as a base, removes a proton from the aqueous complex and becomes the ammonium ion