Experimental procedure 1. Tare a clean and dry 150 mL beaker on a balance. 2. Add about 1 g of copper turnings to the tared beaker, and record the mass of copper in grams, to a precision of 4 decimal places. 3. Place a hot plate with a wire gauze on top of it inside a fume hood to use it later, if needed. 4. Move the beaker with the copper sample into the fume hood (it does not need to be put on the wire gauze on the hot plate). Put on protective nitrile gloves, pull the fume hood sash as far down as you can so that you still may have your hands behind the sash (inside the fume hood) to safely handle the reagents, and then carefully add about 5 mL of 15 M HNO3 from a 10 mL graduated cylinder. ** Caution: 15 M HNO3 can cause severe eye burns and skin burns, and can be fatal if inhaled. Make sure to keep this reagent in the hood, and make sure to pour carefully. If any reagent gets on the outside of a glove or on the benchtop, it must be rinsed thoroughly to minimize the danger. Contact your instructor immediately for assistance.** 5. Carefully swirl the beaker occasionally and make visual observation of any indication that (the redox) reaction is taking place. Record all your observations in your lab notebook. 6. If the entire amount of copper did not react after 4-5 minutes, you may gently heat the beaker (using the hot plate which you have installed inside the fume hood) until you get a clear solution. Record your observations of the final mixture/solution. (Color of the solution? Is it transparent or cloudy? ...). 7. If you heated the reaction mixture, remove the beaker from the hot plate. Away from the hot plate, but still in the hood, add roughly 50 mL distilled water. Record your observations. Leave the hot plate/wire gauze in the hood for use later. 8. Tare a small beaker (a 20 mL or 50 mL beaker, for example) and add to it approximately 5 g of solid sodium carbonate, Na2CO3. 9. To the solution obtained in Step 7 above, start adding solid sodium carbonate in small portions and very carefully, using your spatula. Make sure not to dip the spatula into the solution! Use a glass stir rod to stir well after each small portion of Na2CO3 added. Record your observations. 10. Once additions of solid Na2CO3 no longer cause gas evolution (bubbles), add the rest of sodium carbonate from the small beaker (you can do this all at once or in a couple of large portions) to the reaction mixture and stir well. Record your observations. 11. Assemble a Buchner funnel apparatus for filtration as follows (also see the illustration to the right): Get a ring stand, a clamp, a filter flask with a vacuum seal (a rubber ring for sealing), a Buchner funnel, and a piece of vacuum hose/tubing. Fasten the filter flask to the stand using the clamp. Nest the round filter paper to the bottom of the Buchner funnel and wet it with distilled water. Make sure that the paper fits snuggly to the bottom perforated plate of the funnel. Use the vacuum hose to connect the filter flask to the vacuum nozzle on your bench.

12. Stir the reaction mixture obtained in step 10. with a glass stirring rod, turn on the vacuum by slowly rotating the nozzle, and carefully pour the suspension down the stir rod directed toward the center of the funnel (see the illustration from Step 11). Be sure to keep the stir rod about 1 cm above the filter paper. (If you touch the paper with the tip of the rod, you will likely make a hole in the paper.) 13. Place the stirring rod across the rim of the beaker so that the tip of the rod passes over the spout. Tilt the beaker so that the spout is lowered and the tip of the stirring rod is directed toward the center of the filter cake in the Buchner funnel. Use the jet of distilled water from your wash bottle to rinse thoroughly the inner walls of the beaker and force the particles of the solid down the directed stir rod to the funnel. To see a demonstration of this, please watch the segment between 1:12 1:33 min. of the video at this URL: https://www.youtube.com/watch?v=cgZpMmA- D8Q&ab_channel=JeroenKraan 14. Rinse the filter cake well with distilled water with the suction on, and then leave it on the filter paper with the suction on for an additional 2 minutes. 15. Detach the vacuum hose and shut off the suction. 16. Carefully remove the filter paper with the filter cake from the funnel* and transfer the solid CuCO3 to a clean 150 mL beaker. * Tip: A convenient way to transfer a filter cake out of a Buchner funnel is this: Remove the funnel from the filter flask, cover it with a large watch glass (diameter of the watch glass must be greater than the diameter of the funnel) with its concave side toward the funnel and filter cake (i.e., the watch glass is upside down on top of the funnel piece), and, while pressing the watch glass firmly toward the funnel, turn the funnel and the watch glass up-side-down. The filter paper and filter cake/solid will fall onto the watch glass. If needed, you may gently knock the funnel to make sure that the solid copper(II) carbonate and the filter paper are transferred to the watch glass. After that, you may carefully remove and discard the filter paper or transfer both, CuCO3 and filter paper to the 150 mL beaker for the next procedure. 17. Add about 10 mL of distilled water to the solid in the beaker. If you transferred the filter paper together with the filter cake, use the glass stirring rod to carefully remove all of the solid copper(II) carbonate from the filter paper and then pull the filter paper out from the suspension and discard it. 18. Measure out about 30 mL of 6 M HCl in a 50 mL graduated cylinder, and start adding it, very carefully and in small portions, to the suspension of copper(II) carbonate in the beaker from Step 17. Stir well after each small portion of the acid added. Record your observations. 19. Add about 1.2-1.3 g copper turnings (make sure that you add at least 0.2-0.3 g Cu more than you used in Step 2, at the beginning of the synthesis! Why?). 20. Heat the beaker with the solution and additional elemental copper from Step 19 on the hot plate with wire gauze in the fume hood. 21. Let the reaction mixture simmer until the solution turns clear and yellow or for at least 10 minutes. 22. In the meantime, put about 150 mL distilled water in a clean 400 mL beaker and place the beaker into an ice bath. Also place into the ice bath two additional small beakers, one with about 25 mL distilled water to which 5 drops of 6 M HCl were added, and the other with about 20 mL of acetone. 23. Also in the meantime (while waiting for the reaction mixture in Step 21 to clear up and turn yellow, clean the Buchner funnel and filter flask and reassemble the Buchner funnel apparatus, with a wetted piece of filter paper, for another filtration (See Step 11). 24. After the solution (Step 21) turns yellow and clear, carefully decant the hot (use a hot hand protector to handle the hot beaker) solution down the glass stirring rod into the 150 mL of cold water in the 400-

mL beaker placed in the ice bath (Step 22). Make sure not to transfer any piece of unreacted copper metal. Record your observations. If crystals do not begin to form in the first few minutes after this addition/dilution, initiate the crystallization process by stirring the solution with your glass stir rod. 25. Continue to cool the suspension in the beaker in the ice bath for about 10 minutes. Crystals should continue to form for much of this time, but you will assume crystallization is complete after these 10 minutes. 26. Filter the crystals of CuCl produced in Step 25 using the Buchner funnel apparatus (prepared in Step 23). Quantitatively transfer all the crystals to the Buchner funnel, as described in Steps 12 & 13 above. 27. With the suction on, rinse the filter cake 3 times, each time using about one-third of (~8 mL of) the pre-chilled sample of distilled water with drops 6M HCl added to it from Step 22. Let the suction run for about 30 seconds after each rinse. 28. Turn the suction off and rinse the sample of CuCl on the filter with half of the amount of cold acetone you prepared in Step 22. Wait about 15 seconds and then turn the suction on again. 29. Repeat step 28 with the rest of the cold acetone, and then leave the suction on for 3-4 minutes to dry the crystals. Record all your observations. 30. Tare a dry watch glass (with a diameter greater than the diameter of the Buchner funnel). 31. Turn the suction off, remove the Buchner funnel from the filter flask, and place the tared watch glass, upside down, on top of the funnel to transfer the crystals and the filter paper to the watch glass as described in the tip in Step 16. 32. Carefully remove and discard the filter paper (make sure that there are no crystals adhered to it) and measure the mass of the watch glass with CuCl crystals on it. 33. Discard all the waste to the waste container and clean up. 1. Starting mass of the copper sample (Step 2) 2. Amount (number of moles) of copper at the start of the synthesis (Step 2) (Show your work) 3. Volume of 15 M HNO3 added (Step 4) 4. Amount (number of moles) of HNO3 added (Step 4) (Show your work) 5. Amount (number of moles) of H3O+ ions used during the oxidation of Cu (Steps 4 6; Equation 5) (Show your work) Limiting reactant is (circle the correct answer): Cu H3O+ 6. Amount (number of moles) of H3O+ ions remining in the solution after the total amount of Cu was oxidized (end of Step 6 and Step 7) (Show your work) 7. Total mass of Na2CO3 added (Steps 8 10) 8. Total amount (number of moles) of Na2CO3 added (Steps 8 10) (Show your work) 9 Amount (number of moles) of Na2CO3 used to neutralize the acidic solution (Step 9; Equation 6) (Show your work) Reactant in excess is (circle correct answer): CO32- H3O+ 10 Amount (number of moles) of CO3^2- needed to quantitatively precipitate copper(II) ions from the solution (Step 10; Equation 7) (Show your work) Limiting reactant is (circle the correct answer): CO32- Cu2+