Colours of Transition Elements Flashcards
what is the colour of [Cu(H2O)6]2+?
pale blue
- from CuSO4.5H2O(s)
what colour is Cu(OH)2?
pale blue precipitate
- NH3 dropwise to Cu2+
what is the colour of [Cu(NH3)4(H2O)2]2+?
dark blue
- excess NH3 to Cu2+
what is the colour of CuCl4(2-)?
yellow
- excess HCl to Cu2+
what is the colour of Cu+?
white precipitate from CuI and brown I2
- reduction of Cu2+ with I-
what is the colour of Cu2+/Cu?
brown solid (Cu) and blue solution (CuSO4)
- disproportionation of Cu+
what is the colour of CoCl4(2-)?
blue
- from CoCl2.6H2O(s), water and excess HCl
what is the colour of [Cr(H2O)6]3+?
pale purple
- if heated the solution appears green
- from KCr(SO4)2.12H2O(s), due to impurities it is possible for Cr(III) to appear green
what is the colour of Cr(OH)3?
dark green precipitate
- NH3 dropwise to Cr3+(aq)
what is the colour of [Cr(NH3)6]3+?
purple
- excess NH3 to Cr2+
what is the colour of [Cr(OH)6]3-?
dark green
- excess OH- to Cr(OH)3(s)
what is the colour of Cr2O7(2-)?
orange
- from K2Cr2O7 in 0.1moldm-3 of H2SO4
what is the colour of CrO4(2-)?
yellow
- oxidation of Cr3+ with hot alkaline H2O2
what is the colour of [Mn(H2O)6]2+?
pale pink
- from MnSO4.4H2O(s)
what is the colour of Mn(OH)2?
pale brown precipitate
- NaOH dropwise to Mn2+(aq)
what is the colour of [Fe(H2O)6]2+?
pale green
- from FeSO4.7H2O(s)
what is the colour of Fe(OH)2?
dark green precipitate
- NaOH dropwise to Fe2+(aq)
what is the colour of [Fe(H2O)6]3+?
yellow
- from FeCl3.6H2O(s)
what is the colour of Fe(OH)3?
orange-brown precipitate
- NaOH dropwise to Fe3+(aq)
what is the colour change from MnO4-/Fe2+ to Mn2+/Fe3+?
purple(MnO4-) to pale pink//colourless(Mn2+)
- in titrations it is so dilute that it can appear colourless
what is the colour change from I-/Fe3+ to I2/Fe2+?
orange brown(Fe2+) to brown(I2)
