The provided video demonstrates cleaning copper wire using a chemical solution, likely to remove oxidation and tarnish rather than purifying it in the sense of increasing its copper content. While the video doesn't specify the solution, the general method involves chemical cleaning. True purification, to increase the purity of the copper itself, is typically done through an electrolytic process. This response covers both aspects: chemically cleaning copper wire and electrolytically purifying it.
Cleaning Copper Wire (Removing Oxidation and Tarnish)
The video illustrates a method to clean copper wire, which primarily removes surface impurities like oxidation (tarnish). This is different from purifying the copper itself.
Method:
- Immersion in a Chemical Solution: The copper wire is immersed in a chemical solution. A common household solution is vinegar or lemon juice, both of which are mild acids. Stronger chemical solutions are also available for more stubborn tarnish.
- Reaction and Removal of Impurities: The acid in the solution reacts with the copper oxide (tarnish), dissolving it.
- Rinsing: The wire is rinsed with water to remove any residual chemical solution and dissolved impurities.
- Drying: The wire is dried to prevent further oxidation. The video shows wiping off the excess liquid.
- Result: The copper wire appears brighter and cleaner, as the surface tarnish has been removed, revealing the underlying copper.
Electrolytic Purification of Copper
Electrolytic refining is the most common method to purify copper to a high degree (typically 99.99% purity). This method is used on an industrial scale.
Process:
- Electrolyte: A solution of copper sulfate (CuSO4) acidified with sulfuric acid (H2SO4) is used as the electrolyte.
- Anode: Impure copper is used as the anode (positive electrode).
- Cathode: A thin sheet of pure copper is used as the cathode (negative electrode).
- Electrolysis: When a direct current is passed through the electrolytic cell:
- At the anode, copper dissolves into the solution as copper ions (Cu2+):
Cu (s) → Cu2+ (aq) + 2e- - At the cathode, copper ions from the solution are deposited as pure copper:
Cu2+ (aq) + 2e- → Cu (s)
- At the anode, copper dissolves into the solution as copper ions (Cu2+):
- Impurities: Impurities present in the impure copper anode either dissolve in the electrolyte or fall to the bottom of the cell as "anode sludge." The anode sludge often contains valuable metals like gold and silver, which can be recovered.
- Result: Over time, the impure copper anode dissolves, and pure copper is deposited on the cathode. The purity of the copper at the cathode can reach 99.99%.
Table Summarizing Electrolytic Purification:
| Component | Description |
|---|---|
| Electrolyte | Copper sulfate (CuSO4) solution acidified with sulfuric acid (H2SO4) |
| Anode | Impure copper |
| Cathode | Pure copper sheet |
| Process | Electrolysis |
| Result | High-purity copper (99.99%) at the cathode |
| Anode Sludge | Contains valuable metals like gold and silver |
In summary, cleaning copper wire involves removing surface impurities, while purifying copper involves increasing its copper content through an electrolytic process.
