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Stoichiometry:

Purpose: To determine the concentration of copper (II) sulfate pentahydrate.

Theory:Valuable metals can be recovered from compounds that contain them. Here we will use a more reactive metal, aluminum, to recover the copper from the copper (II) sulfate pentahydrate. The copper (ll) sulfate pentahydrate can be weighted to determine its mass.Then we calculate the moles of copper to determine the moles of copper (II) sulfate pentahydrate.

Materials:

bullet.jpg - 1.0 Kcopper (II) sulfate pentahydrate
bullet.jpg - 1.0 KHydrochloric acid (6M)
bullet.jpg - 1.0 Kvolumetric flask 
bullet.jpg - 1.0 KPipette 10ml 
bullet.jpg - 1.0 K250ml beaker 
bullet.jpg - 1.0 KAluminium foil
bullet.jpg - 1.0 Kfiltration apparatus 
bullet.jpg - 1.0 Kfilter paper 
bullet.jpg - 1.0 KBalance 
bullet.jpg - 1.0 KRubber policeman

Procedure:

1. Obtain about 30 ml of copper (II) sulfate pentahydrate solution from the stock solution provided by your teacher. This solution is quite concentrated. 

2. Pipette 10 ml of this solution into a 100 ml volumetric flask, this will DILUTE the solution, so use proper dilution techniques.

3. Pour this entire solution into a 250 ml beaker, and rinse the volumetric flask 3 times with water, and add the water you used to rinse to the 250 ml beaker instead of throwing it down the sink.

4. Add 20 ml of [6.0] HCl.

5. Obtain a 5 x 5 cm2 of Al foil, scrunch it up, not too tightly, and toss it into the 250 ml beaker. Wait until the blue solution disappears. If there is any blue solution left after the Al is used, then add more Al until the solution goes clear. If you still see extra aluminum flakes floating about, add more HCl until they are no longer there.

6. While you wait for the reaction to complete, set up a filtration apparatus. Don't forget to put your name on the paper and to weigh it first.

7. Filter the contents of the 250 ml beaker and place the copper in the oven to dry overnight. Weigh the copper the next day.

DATA:
 
 
Filter Paper weight (with name on it)
Weight of filter paper with copper (dry)
Volume of pipette for dilution

Questions:

1. By what factor was your copper (II) sulfate diluted?

2. What is the moles of copper precipitated?

3. What are the moles of copper (II) sulfate reacted?

4. What is the diluted concentration of copper (II) sulfate?

Conclusion:

1. What is the concentration of copper (ll) sulfate pentahydrate?

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                                                                                             Created by: 
                                                                                            Deanne Duff 
Last updated, May 18, 2000                                    Nicole Noseworthy