All Colours

Question 1

[Cu(H2O)6]2+

Answer 1

Pale blue solution

Question 2

Cu(OH)2

Answer 2

Pale Blue Precipitate
Formed when NH3 is added dropwise to Cu2+ (aq)

Question 3

[Cu(NH3)4(H2O)2]2+

Answer 3

Dark blue solution
Formed when EXCESS NH3 is added to Cu2+

Question 4

(CuCl4)2-

Answer 4

Yellow solution
Formed when excess HCl is added to Cu2+

Question 5

Cu+

Answer 5

White Precipitate (CuI)
Formed from reduction of Cu2+ with I- (Brown I2 also present)

Question 6

Cu2+/Cu

Answer 6

Brown solid (Cu) and blue solution (CuSO4)
Disproportionation reaction.

Question 7

(CoCl4)2-

Answer 7

Blue Solution
From CoCl2.6H2O + water and excess HCl

Question 8

[Cr(H2O)6]3+

Answer 8

Pale purple solution
Turns green upon heating. Due to impurities it often appears green in solution.

Question 9

Cr(OH)3

Answer 9

Green/Grey precipitate.
Formed whem NH3 is added dropwise to Cr3+(aq)

Question 10

[Cr(NH3)6]3+

Answer 10

Purple solution
Formed when excess NH3 is added to Cr2+ (aq).

Question 11

[Cr(OH)6]3-

Answer 11

Dark green solution
Formed when excess OH- is added to Cr(OH)3

Question 12

(Cr2O7)2-

Answer 12

Orange solution
Formed from K2Cr2O7/H+

Question 13

(CrO4)2-

Answer 13

Yellow solution
Formed from oxidation of Cr3+ with hot alkaline H2O2

Question 14

[Mn(H2O)6]2+

Answer 14

Pale pink solution
Formed from MnSO4.4H2O

Question 15

Mn(OH)2

Answer 15

Pale brown precipitate
Formed when NaOH is added dropwise to Mn2+

Question 16

[Fe(H2O)6]2+

Answer 16

Pale green solution
From FeSO4.7H2O

Question 17

Fe(OH)2

Answer 17

Dark green precipitate
Formed when NaOH is added dropwise to Fe2+

Question 18

[Fe(H2O)6]3+

Answer 18

Yellow solution
From FeCl3.6H2O

Question 19

Fe(OH)3

Answer 19

Orange- brown precipitate
Formed when NaOH is added dropwise to Fe3+(aq)

Question 20

(MnO4)-/Fe2+ –> Mn2+/Fe3+

Answer 20

Purple –> Pale pink (basically colourless due to low conc)

Question 21

I-/Fe3+ –> I2/Fe2+

Answer 21

Orange brown –> Brown