Transition metal Copper reactions

Question 1

[Cu(H2O)6]+2OH small amount
Colour change?
Acid base or ligand substitution?

Answer 1

[Cu(OH)2(H2O)4] +2H2O
Pale blue solution to blue precipitate.
Acid base reaction- 2 H2O ligands are deprotonated to form 2 hydroxide ligands.
2OH- added act as bases, each accepting a H from the deprotonated H2O, and are converted into 2H2O

Question 2

[Cu(H2O)6]+2NH3 small amount
Colour change?
Acid base or ligand substitution?

Answer 2

[Cu(OH)2(H2O)4] +2NH4+
Pale blue solution to blue precipitate
Acid base reaction- 2 H2O ligands are deprotonated to form 2 hydroxide ligands
2NH3 molecules added receive H from the deprotonated H2O, acting as a base.

Question 3

[Cu(OH)2(H20)4]+4NH3 (excess via precipitate intermediate)
Colour change?
Acid base or ligand substitution?

Answer 3

[Cu(NH3)4(H2O)2] +2OH- +2H2O
Blue precipitate to deep blue solution
Ligand exchange occurs

Question 4

[Cu(H2O)6]+4NH3 (excess not via precipitate intermediate)
Colour change?
Acid base or ligand substitution?

Answer 4

[Cu(NH3)4(H2O)2] + 4H2O
Pale blue solution to deep blue solution
Ligand exchange occurs

Question 5

[Cu(H2O)6]+4Cl
Colour change?
Acid base or ligand substitution?

Answer 5

[CuCl4]2- + 6H2O

Pale blue solution to yellow solution