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. Calculate the exact mass of the hydrated sample used.
5. Set up your ring stand with a small iron ring and clay triangle.
6. Place your crucible (without lid) to fit snuggly within the clay triangle.
7.  Adjust your iron ring to hover right above the Bunsen burner to prevent the need for a large flame.
8. 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.
9. Gently heat the crucible containing the hydrated sample without the lid.
10. Heat until the blue crystals turn brown. Be careful to not overheat the compound. If the sample turns black, it has been overheated.
11. 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.
12. Turn off the Bunsen burner and cover the crucible with its lid to prevent rehydration. Allow the sample to cool for approximately ten minutes.
13. 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.
14. Measure the mass of the crucible without its lid and the remaining dehydrated salt.
15. Calculate the mass of the dehydrated sample.
16. Carefully pour anhydrous salt (dehydrated sample) into a 100 mL beaker.
17. 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.
18. Stir until fully dissolved (light blue solution).
19. Cut ~13 cm of aluminum wire and make a small coil using your smallest finger.
20. Fully submerge the coiled aluminum wire into the light blue solution & cover with parafilm. Store in the fume hood until the reaction has completed.
21. Allow the solution to react until the next class session. Copper will start to form as a reddish-brown solid. —– Stop here. While waiting – make the following calculations & insert into your data table – a) Determine the mass of water removed from the hydrated sample b) Determine the moles of water removed from the hydrated sample c) Determine the mass percent of water in the hydrated sample
22. Obtain a piece of dry filter paper & label with your name.
23. Record the mass of the dry filter paper.
24. Remove your solution from the fume hood. Once your solution has fully reacted (evidenced by a lack of blue color and increase in reddish-brown solid), remove your beaker containing the copper & solution from the fume hood. Slowly add ~5 drops of 6 M HCl to the reddish-brown solid. It should start to dissolve and separate from the remaining aluminum wire lodged in the middle of the reddish-brown solid.
25. Remove any remaining reddish-brown solid with a glass stirring rod and let all loose solid remain in the beaker containing the solution.
26. Remove the excess aluminum wire with tweezers and place in the proper disposal container.
27. Take your solution containing the loose reddish-brown solid to the vacuum filtration setup along with your dry filter paper & watch glass.
28. Seal the filter paper to the vacuum filtration setup by adding approximately 5-mL DI water. Allow it to suction for approximately 1 minute.
29. Add the reddish-brown solid (copper) & solution to vacuum filtration. Turn on the filter & allow the copper to fully separate from the solution.
30. Add ~10 mL 95% ethanol to the separated copper on top of the vacuum filtration setup and let it continue suctioning for an additional 2 minutes.
31. Transfer the copper sample and filter paper to the watch glass & place in the drying oven.
32. Allow the sample to dry for approximately 5 minutes, periodically checking its complete dryness. Break the solid up using the spatula to confirm it has been dried inside & continue to dry if needed.
33. Once dry, remove the filter paper containing the copper from the watch glass & record its final mass.
34. Calculate the mass of the copper removed from the hydrate sample.
35. Finish the remaining calculations needed to complete your data table: moles of copper, mass of chlorine, & moles of chlorine.