Reduction and Recovery of Copper Name Here March 18, 2015 Purpose: The goal of this experiment was to use redox chemistry to obtain a sample of copper from a copper (II) sulfate solution. This was accomplished by adding zinc to the copper (II) sulfate solution so that the zinc bonds to the sulfate and leaves copper. Method: To obtain copper from a copper (II) sulfate solution, the copper needs to go through reduction; this means another element has to go through oxidation. For this experiment, zinc was the element going through oxidation. First, we had to calculate how many grams of copper (II) sulfate we needed to form 100 mL of a 0.200 M solution of copper (II) sulfate.
Extraction and Drying: Using a separatory funnel, the cooled filtrate was extracted with 10ml of methylene chloride. After shaking our mixture, we broke and dried our emulsion by slowing passing the lower layer through a cotton ball layered with anhydrous magnesium sulfate. The extraction process was repeated 2 more times for maximum collection of the organic layer. Distillation: The extracts were poured into a 50ml round bottle flask and connected to a simple distillation apparatus. To obtain the caffeine, the methylene chloride was removed from the extract, leaving us with our solid caffeine residue.
We weighed the resulting powder to be 3.228 grams. We then transferred the powder nutmeg into a 50 ml round bottom flask and added 15 ml of dichloromethane. We placed our flask in to a standard heat reflux apparatus and gently refluxed the mixture. We waited until we saw the first drip of liquid in the apparatus and heated for 15 minutes. After the mixture was heated, there was solid on the bottom and liquid on the top of the flask.
* Pour a little ether over the nutmeg residue on the filter paper so that any Diethyl ethanol traces clinging to it is washed down and mixed with the filtered liquid underneath. * Filter the mixture by gravity filtration, washing the nutmeg residue with 10ml of diethyl ether. Evaporate the Ether from the filtrate * Recrystallize the product from ethanol. Filter using a Buchner funnel and wash them with cold water as shown in the diagram (see figure 2). * Let the crystals dry for one week, record the weight and take a sample and put into a glass capillary tube to obtain a melting point using the Melt-Temp machine.
5 mL of 6 M HNO3 was added in beaker to react with copper. Secondly, after 10 mL of distilled water was added, 6 M NaOH was added drop wise until the drop of solution turned red litmus paper blue. Thirdly, the solution was heated with 200 degree until reaction occurs. The reaction mixture cooled to room temperature after continued heated for five minutes. Then, 10 mL of distilled water was added to the precipitate.
Transfer the extracts to a simple-distillation assembly and distill off all but 10 mLof the solvent on a steam bath. Save the recovered solvent. Evaporate the combined solutions to dryness on a steam bath or hot-water bath in a hood. To purify the crude product, dissolve it in about 5 mL of acetone by warming the mixture on a steam bath; add dropwise just enough mixed “hexanes” to turn the warmed solution faintly cloudy; then allow the solution to cool and allow the product to crystallize. Collect the green-tinged crystals on a small vacuum filter and wash them with a little mixed “hexanes.” The melting point of caffeine reported in the literature is 236°.
Gently stir the pellets until the acid is dissolved by shaking the the apparatus. Lift the calorimeter lid and wash out its contents and the thermometer. Repeat this experiment using 50.0 mL of 1.0M acetic acid. Repeat experiment using 25.0 mL of each 2.0M sodium hydroxide and 2.0M acetic acid. Data Table(s): Reaction equation Mass of solid NaOH Initial Temp.
• Second, you close one end of the tube with a clamp. • Third, you place 10 ml. of solution A,B,C into separate dialysis bags with a pipet. (Solution A- with sucrose, solution B with twice as much sucrose, and solution C containing water.) • Fourth, clamp the other end of tubing, leaving about a 2 cm.