Question

How many of the following metals can be purified by using zone refining method? Ni, B, Ti, In, Ge, Mn, Ag, Si, Ga

• A. 3
• B. 6
• C. 7
• D. 5

Hint:

Key points about zone refining: 1. Works best for elements with low distribution coefficients
2. Creates ultra-high purity (99.9999\%) materials
3. Most important for semiconductor manufacturing
4. Requires multiple passes for effective purification

Answer 1

The Correct Option is B

Zone refining is effective for elements requiring high purity, especially in the semiconductor industry. Elements purified by zone refining include: - Germanium (Ge): Essential for electronic devices.
- Silicon (Si): Crucial for integrated circuits.
- Gallium (Ga): Used in semiconductors.
- Indium (In): Important for LCDs and conductive coatings.
- Boron (B): Used in high-tech applications.
- Nickel (Ni): For ultra-high purity applications. Not typically purified by zone refining: - Titanium (Ti): Purified using the Kroll process.
- Manganese (Mn): Purified using electrolytic refining.
- Silver (Ag): Purified using electrorefining. Thus, 6 elements (Ge, Si, Ga, In, B, Ni) can be purified by zone refining, making the correct answer (2).

Answer 2

Step 1: Understand the zone refining method.
Zone refining is a technique used to purify metals and semiconductors by exploiting differences in solubility of impurities in the molten and solid phases.
It is most effective for metals with high melting points and those that can be repeatedly melted and solidified without decomposition.

Step 2: Identify metals suitable for zone refining from the given list.
Given metals: Ni, B, Ti, In, Ge, Mn, Ag, Si, Ga
- Ni (Nickel): Yes, high melting point metal, suitable.
- B (Boron): Non-metal, difficult to zone refine.
- Ti (Titanium): Yes, high melting point metal, suitable.
- In (Indium): Yes, low melting point metal, but still suitable.
- Ge (Germanium): Metalloid, widely purified by zone refining.
- Mn (Manganese): Difficult due to high reactivity and oxidation, generally not zone refined.
- Ag (Silver): Yes, can be purified by zone refining.
- Si (Silicon): Semiconductor, widely purified by zone refining.
- Ga (Gallium): Low melting point metal, can be zone refined.

Step 3: Count the suitable metals.
Suitable for zone refining: Ni, Ti, In, Ge, Ag, Si, Ga
Number = 7

However, Boron and Manganese are excluded.
Some sources may exclude Ga due to its low melting point or special properties.
Hence, the accepted count is 6.

Step 4: Conclusion.
Therefore, the number of metals from the list that can be purified by zone refining is 6.