Laboratory Preparation & Procedure

Materials:

• Crucible and lid
• ring stand
• clay triangle
• iron ring
• crucible tongs
• analytical balance
• solid copper hydrate sample
• 100 mL beaker
• deionized water
• aluminum wire 6 M HCl
• glass stirring rod
• filter paper
• watch glass
• tweezers
• drying oven
• parafilm
• spatula
• vacuum filtration setup
• Bunsen burner
• striker
• 95% ethanol
• rulers
• sharpies

Safety:

Crucibles get extremely hot and can cause burns when heated, handle with care. 6 M HCl is corrosive and a known irritant. Wear protective gloves and wash hands thoroughly after use. 95% ethanol is a highly flammable liquid. Keep container tightly closed & away from sparks or open flames.

Procedure:

1. Dry and weigh the clean crucible without the lid.
2. Use a spatula to add ~1.00 g of the blue hydrated sample directly to the crucible. Break up any large chunks of sample using the spatula.
3. Record total mass of crucible and hydrate.
4. Set up your ring stand with a small iron ring and clay triangle.
5. Place your crucible (without lid) to fit snuggly within the clay triangle.
6.  Adjust your iron ring to hover right above the Bunsen burner to prevent the need for a large flame.
7. Connect your Bunsen burner to the gas line and light the burner away from the crucible. Adjust your Bunsen burner as needed to produce the small blue flame.
8. Gently heat without the lid.
9. Heat until blue crystals turn brown. Be careful to not overheat the compound. If the sample turns black, it has been overheated.
10. Gently tap or slightly shift the crucible to help expose more of the sample’s interior to heat and ensure complete dehydration. Do not use a spatula or glass stir rod to stir the sample—it will likely stick, and you could lose material.
11. Turn off the Bunsen burner and cover the crucible with its lid to prevent rehydration. Allow the sample to cool for approximately ten minutes.
12. After allowing the crucible to cool for about 10 minutes, gently touch the side to check if it has returned to room temperature. Once cool, remove the lid and examine your sample. If you notice any remaining blue-green crystals, reheat the crucible until all the crystals have turned brown, indicating complete dehydration.
13. Measure the mass of the crucible and anhydrous salt.
14. Carefully pour anhydrous salt into a 100 mL beaker.
15. Add ~20 mL of deionized water to the beaker. Rinse out any residual solid that may remain in the crucible with a few mL of deionized water and transfer to the beaker.
16. Stir until fully dissolved (light blue solution).
17. Submerge ~13 cm of aluminum wire into the solution as a coil.
18. Cover with parafilm and allow the solution to react until the next class session. Copper will start to form as a reddish-brown solid. —– Stop here.
19. Remove your beaker containing the copper & solution from the fume hood. Slowly add ~5 drops of 6 M HCl.
20. Carefully remove the excess aluminum wire with tweezers & the glass stirring rod. Rinse any loose copper into the beaker.
21. Record the mass of the dry filter paper and watch glass together.
22. Seal the filter paper to the vacuum filtration setup by adding approximately 5 mL DI water. Allow it to suction for approximately 1 minute.
23. Add the copper & solution to vacuum filtration. Turn on the filter & filter the solid copper.
24. Rinse the copper with ~10 mL 95% ethanol and let it continue suctioning for an additional 2 minutes.
25. Transfer the copper sample and filter paper to the watch glass.
26. Let the sample dry completely on the watch glass in warm oven.
27. Find the mass of the dried copper.