OCR Chemistry A-level Transition Metal complex colours

Colour when Cu2+ is added with NaOH dropwise/excess

Cu(OH)2 - Pale Blue ppt

Fe2+ with NaOH dropwise

Fe(OH)2 - Dark Green ppt

Fe2+ in excess NaOH

Same as dropwise - insoluble in excess - Dark Green ppt

Mn2+ with NaOH dropwise

Mn(OH)2 - pale brown ppt

Mn2+ with excess NaOH

Insoluble in excess NaOH - same as dropwise - pale brown ppt

Fe3+ with NaOH dropwise

Fe(OH)3 - Orange/Brown ppt

Fe3+ with NaOH excess

Insoluble in excess - same as dropwise - orange/brown ppt

Cr3+ with NaOH dropwise

Cr(OH)3 - grey green ppt

Cr3+ with excess NaOH

[Cr(OH)6]2- - dark green solution

Cu2+ and NH3 dropwise

Pale blue ppt

Cu2+ with NH3 excess

[Cu(H2O)2(NH3)4]2+ - Ppt dissolves - deep blue

Fe2+ with NH3 dropwise

Fe(OH)2 (s) - Green ppt

Fe2+ with excess NH3

Fe(OH)2 (s) - green ppt

Fe3+ with NH3 dropwise

Fe(OH)3 (s) - Orange/Brown ppt

Fe3+ with NH3 excess

Fe(OH)3 (s) - Orange/Brown ppt

Mn2+ with NH3 dropwise

Mn(OH)2 - pale brown ppt

Mn2+ with excess NH3

Mn(OH)2 - pale brown ppt

Cr3+ with NH3 dropwise

Cr(OH)3 (s) - Grey-green ppt

Cr3+ with excess NH3

[Cr(NH3)6]3+ - purple solution