Electrolysis and Metal Extraction
Electrolysis is a process that uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. In metallurgy, it's a crucial technique for extracting metals from their ores or compounds, especially when other methods like smelting are not suitable.
Extraction of Reactive Metals
Highly reactive metals, like Sodium (Na), Potassium (K), Magnesium (Mg), and Aluminum (Al), have a strong affinity for non-metals (like oxygen or chlorine). Their compounds are very stable, making it difficult to extract the pure metal using simple chemical reduction (like heating with carbon). For these metals, electrolysis of their molten compounds is the preferred industrial method. Melting is necessary because the molten state allows the ions to move freely and conduct electricity.
Analyzing the Options
Let's look at the extraction methods for the metals listed:
- Copper (Cu): While copper can be purified using electrolysis (electrorefining), its primary extraction from ores often involves smelting (heating with a reducing agent like carbon) and other processes. It's not typically extracted from a molten compound via electrolysis for initial production.
- Gold (Au): Gold is usually extracted using chemical methods like cyanide leaching, followed by precipitation or electrolysis of the resulting solution, not typically from a molten compound.
- Tin (Sn): Tin is primarily extracted by smelting its ore (cassiterite, \(SnO_2\)) with carbon in a furnace.
- Sodium (Na): Sodium is a highly reactive alkali metal. It is commercially extracted by the electrolysis of molten sodium chloride (\(NaCl\)) in a process known as the Downs Process. This method is specifically designed for the electrolysis of molten salts to obtain reactive metals.
The Downs Process for Sodium Extraction
In the Downs Process:
- Molten sodium chloride (\(NaCl\)) is used as the electrolyte. Calcium chloride (\(CaCl_2\)) is often added to lower the melting point, reducing energy costs.
- The electrolysis occurs in a specialized cell at temperatures around \(600^\circ C\).
- At the cathode (negative electrode), sodium ions (\(Na^+\)) gain electrons to form molten sodium metal: \(Na^+ + e^- \rightarrow Na_{(l)}\)
- At the anode (positive electrode), chloride ions (\(Cl^-\)) lose electrons to form chlorine gas (\(Cl_2\)): \(2Cl^- \rightarrow Cl_2_{(g)} + 2e^-\)
This method is widely used because it efficiently produces pure sodium metal.
Conclusion
Based on the analysis, Sodium (Na) is the metal among the given options that is widely extracted by the electrolysis of its molten compound (molten \(NaCl\)).
Similar Questions
Which one among the following metals is not stored under oil ?
Important Questions from Metals & Non-metals
Due to improper/indiscriminate disposal of hold and used computers or their parts, which of the following are released into the environment as e-waste?
1. Beryllium
2. Cadmium
3. Chromium
4. Heptachlor
5. Mercury
6. Lead
7. Plutonium
Select the correct answer using the codes given below:
Recently, there has been a concern over the short supply of a group of elements called 'rare earth metals'. Why?
1. China, which is the largest producer of these elements, has imposed some restrictions on their export.
2. Other than China, Australia, Canada and Chile, these elements are not found in any country.
3. Rare earth metals are essential for the manufacture of various kinds of electronic items and there is a growing demand for these elements.
Which of the statements given above is/are correct?
Which of the following metals CANNOT be cut with a knife?
Which of the following will be formed when dilute hydrochloric acid is added to a beaker having copper oxide ?
Which of the following statement is incorrect regarding metals?
