Question

The purpose of this experiment is to prepare tetraamminecopper (II) sulfate monohydrate by making a reaction between ammonia and copper (II) sulfate pentahydrate in an aqueous solution. When the reaction is complete, the product is then isolated and percent yield is determined. We had to weigh CuSO₄ 5H₂O and then mix it with water then heat. Ammonia is then added once the solid dissolves and is heated to a gentle boil. The solution is then put into a buchner funnel and drained of all liquid with a water aspriator. The solid remaining is cleaned off with ammonia and ethanol solution and then just pure ethanol. The solid remaining is weighed. 1. What did you expect to happen and what actually happened? Why did it

2. What is your interpretation of the physical and chemical changes observed

during the experiment?

3. What type of chemical reaction was performed? Is there any physical evidence

that the reaction happened?

4. How did you know the reaction was over?

5. Considering the collected data, identify the type of problem that you’re working

with (simple stoichiometry, limiting reactant and/or percent yield) and describe

the steps needed to solve it. Integrate your calculations to show how identifying

the problem guides your solution.

6. Were you able to identify the limiting reagent?

7. What is the meaning of the % yield obtained? Could it be better?

8. What is your interpretation of the chemical equation (think about mole

9. Will the opposite reaction take place (water replacing ammonia ligands)?

10. Explain (Consider the properties of the chemicals involved and the nature of the

observed chemical reaction)

11. Could this reaction be performed in the solid phase? Why solutions are needed?

12. How could you improve the results?

13. Any other topics you consider important to this experiment.

Answer 1

Cuso4.5H2O(aq.) + 4NH3(aq.) - - - - > Cu(NH3)4SO4.H2O + H2O

1.. We can expect from this reaction or we can say by heating the copper sulphate , it will be dehydrated and turns blue to white color. But here 4NH3 molecule replace the 4 H2O molecules Because the product is a coordination compound which is more stable and deep blue colour.

2.. Physical interpretation - light blue color of solution converted into deep blue color because Cu(NH3)4SO4.H2O have deep blue color.

Chemical interpretation - it is observed that product is a coordination compound then it gives only ions in the solution [Cu(NH3)4]2+ and SO4 2- ions

3.. This is the reaction of type in which coordination compound is formed and NH3 ligand substitute the H20 molecules.

Physical evidence - change in color.

4.. Reaction over indication - all light blue color convert into deep blue color and no further darker color.