Ion colours Flashcards
1
Q
Cu2+ (aq)
A
pale blue solution
2
Q
Cr3+
A
violet solution
3
Q
Fe2+
A
pale green solution
4
Q
Fe3+
A
yellow solution
5
Q
Mn2+
A
pale pink solution
6
Q
Cu2+ in OH-/NH3
A
- pale blue PPT
- [Cu(OH)2(H2O)4]
7
Q
Cr3+ in OH-/NH3
A
- dark green PPT
- [Cr(OH)3(H2O)3]
8
Q
Fe2+ in OH-/NH3
A
- Dark green PPT
- [Fe(OH)2(H2O)4]
9
Q
Fe3+ in OH-/NH3
A
- orange-brown PPT
- [Fe(OH)3(H2O)3]
10
Q
Mn2+ in OH-/NH3
A
- pale brown PPT
- [Mn(OH)2(H2O)4]
11
Q
What are the 2 transition metals that change colour in excess NH3?
A
- Cu2+ is dark blue solution [Cu(NH3)4(H2O)2]2+
- Cr3+ is a purple solution [Cu(NH3)6]3+
12
Q
What is the only transition metal that changes colour in excess OH-?
A
Cr3+ becomes dark green solution [Cr(OH)6]3-
13
Q
excess HCl + Cu2+
A
CuCl4 2-
yellow solution
14
Q
Cu2+/ Cu
A
- disproportionation of Cu2+ forms brown solid (Cu) and blue solution (CuSO4)
15
Q
CoCl2.6H2O + excess HCl
A
CoCl4 2-
blue
16
Q
Cr2O7 2-
A
- from K2Cr2O7 in 0.1 dm3- H2SO4
- orange
17
Q
CrO4 2-
A
- oxidation of Cr3+ w/ hot alkaline hydrogen peroxide
- yellow
18
Q
MnO4-/Fe2+ to Mn2+/Fe3+ titration
A
-purple MnO4- to pale pink Mn2+
19
Q
I-/ Fe3+ to I2/ Fe 2+ titration
A
orange brown Fe3+ to brown I2
