Aluminum & Copper (II) Sulfate Redox Lab

Aluminum & Copper (II) Sulfate Redox Lab

Purpose:

• To determine the number of grams of Cu that will be produced from an oxidation reduction reaction when you know the mass of Al that reacted with a known amount of CuSO₄ * 5H₂O and to compare this to the actual yield of Cu.
  

In our lab, we found that Al is the limiting reactant (Al - 0.003 mol Cu; CuSO₄ - 0.509 mol Cu). With that information, we found that the limit is 0.191 g Cu. We then found our theoretical yield which turned out to be 1.6 g of Cu. Our actual yield was 1.59 g Cu. Then we found our percent yield -- 99.38%.

Materials:

• Safety goggles
• Apron
• Medium sized (75-100ml) beaker
• 75ml H₂O
• 9.36g CuSO₄
• 0.45g Al
• Bunsen Burner
• Filter paper
• Weighing paper
  
• Scale
• Erlenmeyer flask
• Filter
• Paper towel
  

SAFETY FIRST!

Don't forget to wear your aprons and goggles and ALWAYS have a glass disposal unit on-hand. Also, in this lab we worked with heat. Be sure to take the proper precautions (use tongs or heat mitt when handling objects which have been heated.)

Doing the Lab

The first step in successfully completing this lab was obtaining a medium sized beaker. We then got a granulated cylinder to measure our water (because everyone knows that beakers don't give very accurate measurements.) We made sure to measure our water very carefully and got 75ml of Water (H₂O). I then went to the chemicals counter and got a random amount of Copper (II) sulfate pentahydrate (CuSO₄)on weighing paper. I took it back to our lab station and measured it out to 9.36g. I then took all of the CuSO₄ off of the paper, measured the paper, and found the difference which was 9.15g. After that, we turned on the Bunsen burner, and stirring the water, we slowly added the CuSO_4. While Jasmine was stirring the mixture, I went to the chemical counter again and got some Al. Again I measured it out then subtracted the weight of the filter paper for a final weight of 0.45g. By then the water was heated and the CuSO₄ was all dissolved in it (making the chemical equation CuSO₄ * 5H₂O). I very carefully added the Al to the solution whilst Jasmine was still stirring and waited for the Al to completely dissolve in the CuSO₄ * 5H₂O. After it was all dissolved, we waited 3 minutes then removed our mixture from the heat. We then got a piece of filter paper, folded it, and poured our CuSO₄ * H₂ + Al mixture into the filter until it was all out of the cup (after we got down to the bottom where all of the Cu was left over we had to add just a little bit of water so we could be sure we got the most accurate results.) We then waited until all of the liquid was out, and we took the filter out. We set the filter on a paper towel (with our names on it, just in case the mixture had smudged our names on the filter paper) and cleaned our lab station.

The next day we came back and got our filter paper with the dried Cu on it. We measured the weight on a scale down to the thousandths place and got 1.8 grams. Then, we subtracted the weight of the filter paper (.21 g, remember?) and got an answer of 1.59 g Cu.

Results:

• Limiting Reactant Results:
  
• CuSO₄ = 0.509mol Cu
• Al = 0.003mol Cu********* = limiting reactant
  
• 0.003mol Cu = 0.191g Cu

• Theoretical Yield:
• 1.6g Cu
• Actual Yield:
• 1.59g Cu
• Percent Yield:
• 99.38%
  

Analysis:
1) Write the balanced reaction equation.

• 3CuSO₄ + 2Al ----> Al₂(SO₄)₃ + 3Cu

2) Write the net ionic equation

• ???

3) What is the reducing agent and what is the oxidizing agent?

• ???

4) Use the mass of the aluminum foil and calculate the mass of the copper you theoretically would form.

• 1.6 g Cu

5) Subtract the filter paper from the dry residue/product in the data table below. This is your actual yield of copper.

• 1.8-0.21=1.59 g Cu

6) Calculate the percent yield of this experiment.

• 1.59/1.6 x 100 = 99.38%

7) Give three reasons of why the amount of copper that should have formed and the amount of copper that actually formed might be different.

• We may have been off in our measuring just a little bit.
• Some of the Al may have stuck to the filter paper.
• Some of the Cu may have been stuck to the