5.3 - transition element colours

Question 1

Fe2+

Answer 1

green

Question 2

Fe(OH)2

Answer 2

green pecipitate

Question 3

Fe3+

Answer 3

yellow

Question 4

Fe(OH)3

Answer 4

orange-brown precipitate

Question 5

Cu

Answer 5

brown

Question 6

Cu+

Answer 6

colourless

Question 7

CuI

Answer 7

white precipitate

Question 8

Cu2+

Answer 8

pale blue

Question 9

[Cu(NH3)4(H20)2]2+

Answer 9

deep blue

Question 10

Cu(OH)2

Answer 10

pale blue precipitate

Question 11

[CuCl4]2-

Answer 11

yellow

Question 12

Cr3+

Answer 12

violet

Question 13

[Cr(NH3)6]3+

Answer 13

purple

Question 14

Cr(OH)3

Answer 14

green precipitate

Question 15

[Cr(OH)6]3-

Answer 15

green

Question 16

Cr2O72-

Answer 16

orange

Question 17

CrO42-

Answer 17

yellow

Question 18

Mn2+

Answer 18

pale pink

Question 19

Mn(OH)2

Answer 19

light brown

Question 20

MnO4-

Answer 20

purple

Question 21

[Cu(H2O)6]2+ + 4Cl- (reagent: conc HCl)

Answer 21

[CuCl4]2- +6H2O

Question 22

[Cu(H2O)6]2+ + 4NH3 (reagent: excess NH3)

Answer 22

[Cu(NH3)4(H2O)2]2+ + 4H20

Question 23

[Cr(H20)6]3+ + 6NH3 (reagent: excess NH3)

Answer 23

6H20 +[Cr(NH3)6]3+

Question 24

notes on precipitation reactions:
Cu(OH)2

Answer 24

Redissolves in excess NH3 to give deep blue [Cu(NH3)4(H2O)2]2+

Question 25

notes on precipitation reactions:
Cr(OH)3, excess NH3

Answer 25

purple [Cr(NH3)6]3+

Question 26

notes on precipitation reactions:
Cr(OH)3, excess OH-

Answer 26

green [Cr(OH)6]3-