Coordination chemistry of copper,cobalt,nickel and silver.

Part I.
A.Copper and Nickel Ions:
Record the colors of the following solutions:

1.CuSO4(aq):

2. [Cu(NH3)4]2+(aq):

3. After HCl addition:

4. NiCl2(aq):

5. [Ni(NH3)6]2+(aq):

6. After HCl addition:

Explain the effects of NH3(aq) and HCl(aq) on the CuSO4 solution in terms of Le Chatelier's Principle. Consider the following equilibria:

[Cu(H2O)4]2+(aq)+ 4NH3(aq) <--> [Cu(NH3)4]2+(aq)+4H2O(l)

[Ni(H2O)6]2+(aq)+6NH3(aq) <--> [Ni(NH3)6]2+(aq)+6H2O(l)

NH3(aq)+ H+(aq) <--> NH4+(aq)

B. Cobalt Ions:

Record the colors of the following solutions:

7. CoCl2(aq):

8. After the addition of HCl(aq):

9. After the addition of H2O:

Account for the changes observed for the cobalt solutions in terms of Le Chatelier's Principle. Consider the following equilibrium:

[Co(H2O)6]2+(aq)+4Cl-(aq) <--> [CoCl4]2-(aq)+6H2O(l)

Part II
10. and 11. Account for your observations. Consider the following equilibria:

10. 2Ag+(aq)+CO32-(aq) <--> Ag2CO3(s)

11. CO32-(aq)+2H+(aq) <--> H2O(l)+CO2(g)

12. Account for your observations. Consider the following equilibria:

2Ag+(aq)+Cl-(aq) <--> AgCl(s)

Ag+(aq)+2NH3(aq) <--> [Ag(NH3)2+(aq)

NH3(aq)+ H+(aq) <--> NH4+(aq)

13. Did the precipitated AgCl dissolve? Explain.

14. What effect did the addition of HNO3 have on the contents of the test tube? Explain.

15. What effect did the addition of NH3 have on the contents of the test tube? Explain.

16. Explain the effect of the addition of KI.

Part III. Effect of Temperature on Equilibria.
Record the colors of the following solutions:

17. Cool CoCl2:

Hot CoCl2:

Is the reaction exothermic? Explain.

Lab Technique and Safety Section:
19. LAB TECHNIQUE: Why is it important to check all glassware before use in the laboratory?

20. LAB SAFETY: When dealing with concentrated NH3 and concentrated HCl, what saftey precautions should you take? If you come in contact with them, what should you do?

Solution Summary

18 Questions on the coordination chemistry of copper,cobalt,nickel and silver are discussed. 2 questions on laboratory safety and technique are discussed. The reasons for color in various media are discussed in terms of coodination geometry of complex ions in solution. Le Chatelier's principle is also studied in these reactions.