5.3.1 Transition Elements

Question 1

[Cu(H2O)6]2+

Answer 1

pale blue solution

CuSO4•5H2O (s) + H2O (l)

Question 2

Cu(OH)2

Answer 2

pale blue ppt

[Cu(H2O)6]2+ (aq) + NH3 (aq) - dropwise

Question 3

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

Answer 3

dark blue solution

Cu(OH)2 (s) + NH3 (aq) - excess

Question 4

[CuCl4]2-

Answer 4

yellow solution

[Cu(H2O)6]2+ (aq) + HCl (aq) - excess

Question 5

CuI

Answer 5

white ppt (CuI) and brown solution (I2)

Cu2+ (aq) + I- (aq) - excess

Question 6

Cu2+/Cu

Answer 6

brown ppt (Cu) and blue solution (CuSO4)

Cu2O (s) + H2SO4 (aq) → Cu (s) + CuSO4 (aq) + H2O (l)

Question 7

[Cr(H2O)6]3+

Answer 7

pale purple solution (green when heated)

KCr(SO4)2•12H2O (s) + H2O

Question 8

Cr(OH)3

Answer 8

dark green ppt

[Cr(H2O)6]3+ + NH3 (aq) - dropwise

Question 9

[Cr(NH3)6]3+

Answer 9

purple solution

Cr(OH)3 (s) + NH3 (aq) - excess

Question 10

[Cr(OH)6]3-

Answer 10

dark green solution

Cr(OH)3 (s) + OH- - excess

Question 11

[Cr2O7]2-

Answer 11

orange solution

K2Cr2O7 (s) + 0.1mol dm-3 H2SO4 (aq)

Question 12

Cr3+

Answer 12

green solution

[Cr2O7]2-(aq) + 3Zn(s) + 14H+(aq) → 2Cr3+(aq) + 7H2O(l) + 3Zn2+(aq)

Question 13

[CrO4]2-

Answer 13

yellow solution

hot H2O2 (aq) + Cr3+(aq)

Question 14

[Mn(H2O)6]2+

Answer 14

pale pink solution

MnSO4•4H2O(s) + H2O (l)

Question 15

Mn(OH)2

Answer 15

pale brown ppt

[Mn(H2O)6]2+ + OH-(aq) - dropwise

Question 16

[Fe(H2O)6]2+

Answer 16

pale green solution

FeSO4•7H2O(s) + H2O(l)

Question 17

Fe(OH)2

Answer 17

dark green ppt

[Fe(H2O)6]2+ + OH- (aq) - dropwise

Question 18

[Fe(H2O)6]3+

Answer 18

yellow solution

FeCl3•6H2O (s) + H2O (l)

Question 19

Fe(OH)3

Answer 19

orange-brown ppt

[Fe(H2O)6]3+ (aq) + OH- (aq) - dropwise

Question 20

Mn2+/Fe3+

Answer 20

purple solution (MnO4-) to pale pink (Mn2+)

MnO4-(aq) + 8H+(aq) + 5Fe2+(aq) → Mn2+(aq) + 5Fe3+(aq) + 4H2O(l)

Question 21

I2/Fe2+

Answer 21

orange-brown solution (Fe3+) to brown solution (I2)

2Fe3+(aq) + 2I-(aq) → 2Fe2+(aq) + I2(aq)