Colours

Question 1

Cr³⁺ or [Cr(H₂O)₆]³⁺

Answer 1

Violet solution

Question 2

[Cr(H₂O)₅SO₄]⁺ (when H₂SO₄ is present)

Answer 2

Green solution

Question 3

Cr²⁺ or [Cr(H₂O)₆]²⁺

Answer 3

Blue solution

Question 4

[Cr(NH₃)₆]³⁺

Answer 4

Purple solution

Question 5

[Cr(OH)₆]³⁻

Answer 5

Dark Green solution

Question 6

Cr(OH)₃ (s)

Answer 6

Grey-Green precipitate

Question 7

Cr₂O₇²⁻

Answer 7

Orange solution

Question 8

Fe²⁺ or [Fe(H₂O)₆]²⁺

Answer 8

Pale Green solution

Question 9

Fe³⁺ or [Fe(H₂O)₆]³⁺

Answer 9

Yellow solution

Question 10

Fe(OH)₂ (s)

Answer 10

Green precipitate

Question 11

Fe(OH)₃ (s)

Answer 11

Orange/Brown precipitate

Question 12

Cu²⁺ or [Cu(H₂O)₆]²⁺

Answer 12

Pale Blue solution

Question 13

[Cu(NH₃)₄(H₂O)₂]²⁺

Answer 13

Dark Blue solution

Question 14

[CuCl₄]²⁻

Answer 14

Yellow solution

Question 15

Cu(OH)₂ (s)

Answer 15

Blue precipitate

Question 16

Mn²⁺

Answer 16

Pale Pink solution

Question 17

MnO₄⁻

Answer 17

Purple solution

Question 18

Mn(OH)₂ (s)

Answer 18

Light Brown precipitate

Question 19

With excess NaOH, only ……. reacts further forming …..

Answer 19

Cr(OH)₃ –> [Cr(OH)₆]³⁻

Grey-Green precipitate –> Dark Green solution

Question 20

With excess NH3, only ……. react further forming …..

Answer 20

Cr(OH)₃ –> [Cr(NH₃)₆]³⁺
Grey-Green precipitate –> Purple solution

Cu(OH)₂ –> [Cu(NH₃)₄(H₂O)₂]²⁺
Blue precipitate –> Dark Blue solution