15: Transition Metals - reactions of ligands

Question 1

(Cr(H2O)6)3+ + sodium hydroxide

Answer 1

(Cr(OH)3(H2O)3)
Green solution –> Green-grey precipitate

Question 2

(Cr(H2O)6)+ + aqueous ammonia

Answer 2

(Cr(OH)3(H2O)3)
Green solution –> Green-grey precipitate

Question 3

(Cr(H2O)6)3 + excess sodium hydroxide

Answer 3

(Cr(OH)6)-3
Green solution –> Green-grey precipitate –> Dark green solution

Question 3

(Cr(H2O)6)+ + excess ammonia

Answer 3

(Cr(NH3)6)3+
Green solution –>Green-grey precipitate –> Purple solution

Question 4

(Cu(H2O)6)2+ + sodium hydroxide

Answer 4

(Cu(OH)2(H2O)4)
Pale blue solution –> Dark blue precipitate

Question 5

(Cu(H2O)6)2+ + ammonia

Answer 5

(Cu(OH)2(H2O)4)
Pale blue solution –> Dark blue precipitate

Question 6

(Cu(H2O)6)2+ + excess sodium hydroxide

Answer 6

(Cu(OH)2(H2O)4)
no further reaction

Question 7

(Cu(H2O)6)2+ + excess ammonia

Answer 7

(Co(NH3)4(H2O)2)2+
Ligand exchange
Pale blue solution –> Dark blue precipitate –> Deep blue solution

Question 8

(Fe(H2O)6)2+ + aqueous ammonia

Answer 8

(Fe(OH)2(H2O)4)
Pale green solution –> Green precipitate
Darkens on standing as precipitate oxidised by water and air to form Iron (III) hydroxide

Question 9

(Fe(H2O)6)2+ + sodium hydroxide

Answer 9

(Fe(OH)2(H2O)4)
Pale green solution –> Green precipitate
Darkens on standing as precipitate oxidised by water and air to form Iron (III) hydroxide

Question 10

(Fe(H2O)6)2+ + aqueous ammonia

Answer 10

(Fe(OH)3(H2O)3)
Yellow solution –> Orange precipitate
Darkens on standing

Question 11

(Fe(H2O)6)2+ + sodium hydroxide

Answer 11

(Fe(OH)3(H2O)3)
Yellow solution –> Orange precipitate
Darkens on standing

Question 12

(Co(H2O)6)2+ + sodium hydroxide

Answer 12

(Co(OH)2(H2O)4)
Pale pink solution –> Blue precipitate
Turns brown on standing

Question 13

(Co(H2O)6)2+ + aqueous ammonia

Answer 13

(Co(OH)2(H2O)4)
Pale pink solution –> Blue precipitate
Turns brown on standing

Question 14

(Co(H2O)6)2+ + excess ammonia

Answer 14

(Co(NH3)6)2+
Ligand exchange
Pale pink solution –> Blue precipitate –> Yellow-brown solution
On standing, turns brown as oxidised to (Co(NH3)6)3+