transition metals

Question 1

[Cu(H2O)6]2+
from CuSO4.5H2O(s)

Answer 1

pale blue solution

Question 2

Cu(OH)2(s)
NH3 dropwise to Cu2+(aq)

Answer 2

pale blue precipitate

Question 3

[Cu(NH3)4(H2O)2]2+
excess NH3 to Cu2+(aq)

Answer 3

dark blue solution

Question 4

CuCl4^2–
excess HCl to Cu2+(aq)

Answer 4

yellow solution

Question 5

Cu+
reduction of Cu2+ with I–

Answer 5

white precpitate (CuI)
and brown I2

Question 6

Cu2+ / Cu
Disproportionation of Cu+

Answer 6

brown solid (Cu) and
blue solution (CuSO4)

Question 7

CoCl4^2–
from CoCl2.6H2O(s) plus
water and excess HCl

Answer 7

blue solution

Question 8

[Cr(H2O)6]
3+
from KCr(SO4)2.12H2O(s)

Answer 8

pale purple

(heat green)
Due to impurities, it is
common for Cr(III) to
appear green in solution

Question 9

Cr(OH)3(s)
NH3 dropwise to Cr 3+(aq)

Answer 9

dark green precipitate

Question 10

[Cr(NH3)6]3+
excess NH3 to Cr 2+(aq)

Answer 10

purple

Question 11

[Cr(OH)6]3–
excess OH– to Cr(OH)3(s)

Answer 11

dark green solution

Question 12

Cr2O72–
from K2Cr2O7(s) in 0.1mol dm-3 H2SO4

Answer 12

orange solution

Question 13

CrO42–
oxidation of Cr3+ with
hot alkaline H2O2

Answer 13

yellow solution

Question 14

[Mn(H2O)6]2+
from MnSO4.4H2O(s)

Answer 14

pale pink solution

Question 15

Mn(OH)2(s)
NaOH dropwise to Mn2+(aq)

Answer 15

pale brown precipitate

Question 16

Mn(OH)2(s)
NaOH dropwise to Mn2+(aq)

Answer 16

pale green solution

Question 17

Fe(OH)2(s)
NaOH dropwise to Fe2+(aq)

Answer 17

dark green precipitate

Question 18

[Fe(H2O)6]3+
from FeCl3.6H2O(s)

Answer 18

yellow solution

Question 19

Fe(OH)3(s)
NaOH dropwise to Fe3+(aq)

Answer 19

orange-brown precipitate

Question 20

MnO4–/Fe2+ Mn2+/Fe3+

Answer 20

purple (MnO4–) to pale pink (Mn2+)

Question 21

I–/Fe3+-I2/Fe2+

Answer 21

orange brown (Fe3+) to brown (I2)