Colours of inorganic ions and complexes

Question 1

[Cu(H2O)6]2+

Answer 1

pale blue solution

Question 2

Cu(OH)2 (s)

Answer 2

pale blue precipitate

Question 3

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

Answer 3

dark blue solution

Question 4

CuCl4 2-

Answer 4

yellow solution

Question 5

CuI

Answer 5

white precipitate

Question 6

CuSO4

Answer 6

blue solution

Question 7

Cu

Answer 7

brown solid

Question 8

CoCl4 2-

Answer 8

blue solution

Question 9

[Cr(H2O)6]3+

Answer 9

pale purple solution (can often look green due to impurities)

Question 10

Cr(OH)3 (s)

Answer 10

dark green precipitate

Question 11

[Cr(NH3)6]3+

Answer 11

purple solution

Question 12

[Cr(OH)6]3-

Answer 12

dark green solution

Question 13

Cr2O7 2-

Answer 13

orange

Question 14

CrO4 2-

Answer 14

yellow solution

Question 15

[Mn(H2O)6]2+

Answer 15

pale pink

Question 16

Mn(OH)2 (s)

Answer 16

pale brown precipitate

Question 17

[Fe(H2O)6]2+

Answer 17

pale green solution

Question 18

Fe(OH)2 (s)

Answer 18

dark green precipitate
(goes rusty brown/orange-brown as it oxidises to Fe(OH)3)

Question 19

[Fe(H2O)6] 3+

Answer 19

yellow solution

Question 20

Fe(OH)3 (s)

Answer 20

orange-brown precipitate

Question 21

MnO4 -

Answer 21

purple

Question 22

Mn 2+

Answer 22

very pale pink (almost colourless in titrations)