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
  

Types of Reactions

Introduction:
(Five types of reactions)

1. Combustion: "Push" required to start, often times a violent reaction, (water and hydrocarbon)
2. Synthesis: Compound formed (Two reactions = one product)
   
3. Decomposition: Cations & anions (One Reactions breaks down to create two products)
   
4. Single Displacement: Metal takes the place of another metal in a compound
5. Double Displacement: Positive and negative of two ionic compounds interchange.

Safety:

• Goggles
  
• Aprons
• Ponytails
• Close-toed shoes
• Everyone was very well behaved throughout the lab
• Made sure to follow directions to a "T"
  

Procedure:

• First, we made sure that our lab kits weren't lacking in any important materials needed for the lab (test tubes, test tube holder, Bunsen burner, striker, test tube rack)
• Next we went to the table with a test tube and got a piece of zinc in a plastic cup and 1/2 mL of CuSO₄. We placed the Zn in the CuSO₄ and recorded the reaction in our warmup journal. (Please see table below!!!)
• The next step was to get the 2nd test tube and add 1/2 mL Ba(NO₃)₂. We recorded our observations.
• With the 3rd test tube, we added a piece of Mg ribbon and poured 1/2 mL of HCl to it. We recorded the observations in the table below.
• The next step in our lab was to light a Bunsen burner (carefully, of course). The blue flame stood about 3 inches high.
• We then rinsed the first test tube thoroughly and added about 2 mL of H₂O₂. We lightly heated it and recorded the observations.
• We then added a pinch of MnO₂ (which is a catalyst) to the H₂O₂ and lightly heated that over the Bunsen burner.
  

Results:

Conclusion:
By observing the multiple reactions that took place in this lab, we were able to identify the types of reactions that took place.

For CuSO₄ + Zn, we determined it was Single displacement. Our identification of this reaction type was brought on by the fact that a precipitate was formed from the existing metal (Zn).

Balanced: Cu + ZnSO₄

For CuSO₄ + Ba(NO₃)₂, it was decided that this was a Double displacement reaction. The foaming bubbles that formed gave us ample evidence of this.

Balanced: BaSO₄ + Cu(NO₃)₂

Our HCl + Mg was also single displacement, determined by the formation of Hydrogen gas (which we found using a lit wooden splint.)

Balanced: H₂ + MgCl₂

H₂O₂ was found to be decomposition by the wooden splint again. This time the fire went out and the embers glowed slightly.

Balanced: 4H₂O + 2O₂

Finally, C₃H₈ + O₂ was a combustion reaction as evident by its strong release of light and heat.

Balanced: 3CO₂ + H₂O

Polarity and Molecular Shape Lab

Objectives

• Construct models of molecules
  
• Determine molecular shapes
• Predict polarity of molecules

Materials

• Molecular model kit

Procedure

• We built a model for each of the listed molecules on the back of our given paper.

CH4	BF3	C3H8	H2O
Si2H6	HF	CH3NH2	H2O2
N2	SeF4	C2H4	SiH2O
IF3	SF6	CO2	SO32

• Drew the three-dimensional structure for each of these molecules
• Then determine each of the molecules; shape, bond angle, polarity, and resonance

Results
(We're sorry - we've tried to fix the blank space, but because of the limited amount of space blogger layouts give us, we can't. Please scroll down. I know it's a hassle, but it's worth it when you get to the bottom. Thanks)

Molecular Formula	Lewis Structure	3-Dimensional Model	Shape	Bond Angle	Polarity	Resonance
CH4		row 1, cell 3	tetrahedral	109°	no	no
BF3		row 2, cell 3	triagular planar	120°	yes	no
C3H8			linear	120°	no	no
H2O			angular	109.5°		yes	no
Si2H6				108.9°	no	no
HF			linear	180°	yes	no
CH3NH2		row 7, cell 3	tetrahedral	120°	yes	no
H2O2		row 8, cell		row 8, cell 4	row 8, cell 5	no	no
N2		row 9, cell 3	linear	180°	no	no
SeF4			seesaw	row 10, cell 5	no	no
C2H4			planar	120°	no	no
SiH2O		row 12, cell 3	trigonal planar	120°	yes	no
IF3			T-shaped	180°	yes	no
SF6			tetrahedral	180°	yes	no
CO2			linear	180°	no	no
SO32-			trigonal planar	104.5°	row 16, cell 6	yes

Chromatography Lab

Paper Chromatography Lab

• We were trying to figure out which solvent out of the four chosen (H₂O, CH₃OH, C₃H₇OH, and C₆H₁₄) would best work to mobilize the components (water-based markers).
  

Hypothesis

• We hypothesized that the C₃H₇OH would be the best solution and move the component farther due to the amount of Hydrogen atoms.

Materials

• H₂O
  
• CH₃OH
  
• C₃H₇OH
  
• C₆H₁₄
  
• Black, Red, Green, Purple, and Blue Overhead Pens
  
• Chromatography Paper (Cut into 1 cm by 8 cm strips)

Safety Precautions

• Goggles
  
• Aprons
  
• To avoid contact with the Hexane we prepped our station before hand and made sure to keep the goggles and aprons fully covering their designated areas. We made extra sure to keep the Hexane in use under the fume hood and to keep our heads away from the fumes.

Procedure

• In Part I of the Chromatography Lab we took four pieces of the Chromatography paper and dotted them three times with a black overhead pen. We then took our well pan to the chemical dispensary fume hood to retrieve the different solvents to use in our experiment. With the caution of the Hexane in mind we took the well pan directly back to our stations' fume hood. We separately labeled the chromatography papers for which solvents they would be placed into and then we put the papers into the separate solvents. After waiting a half an hour we observed the papers with the following results. In order from left to right is H₂O, CH₃OH, C₃H₇OH, and C₆H₁₄.

• In Part II of the Chromatography Lab we choose a solvent which worked best determined in Part I of the lab. (H₂O!) We then took various colors of overhead pens such as Red, Green, Purple, and Blue. Dotted separate chromatography papers for each pen color, then set them in the well plate, already filled with H₂O. We got the following results in the following order; Blue, Purple, Red, and Green

Conclusion

• The results of our experiment show that our hypothesis that C₃H₇OH would work best due to the amount of Hydrogen atoms was incorrect and therefore thrown out.
• H₂O worked the best out of the four given solvents, because of it's polarity.
  
• CH₃OH worked second best
• C₃H₇OH came in third
• And C₆H₁₄ worked the worst.

Learning Experience

• Through this experimental lab we learned that safety precautions are very important when dealing with toxic chemicals. Thus keeping a pair of goggles and an apron on was necessary at all times.

Technical Difficulties

• Any experiment could face difficulties. Our experiment could have been better with a wider range of colors and solvents. We could have compared different solvents to see if we could find one more polar then H₂O. This could have immensely improved our experiment.