Question

Magnesium can be obtained by: (a) Reducing magnesium salt solution with \(\mathrm{Fe}\) (b) Electrolysis of fused magnesium salt (c) Electrolysis of \(\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}\) solution (d) Reducing MgO with coke

Short answer

The correct method is the electrolysis of fused magnesium salt (option b).

Step-by-step solution

Analysis of Option (a)

Option (a) is reducing a magnesium salt solution with iron (Fe). This process is not typically used to obtain magnesium because iron does not effectively reduce magnesium ions in solution to elemental magnesium.

Analysis of Option (b)

Option (b) involves the electrolysis of fused magnesium salt. This method is commonly used to obtain elemental magnesium. During this process, magnesium ions are reduced to magnesium metal at the cathode.

Analysis of Option (c)

Option (c) is about the electrolysis of \(\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}\) solution. Electrolysis of this aqueous solution would result in the evolution of gases rather than solid magnesium, due to the reactions of water electrolysis.

Analysis of Option (d)

Option (d) suggests reducing MgO with coke. While theoretically possible, this method is less common because it requires very high temperatures and is less efficient compared to electrolysis.

Conclusion

Analyzing all options, (b) Electrolysis of fused magnesium salt is the suitable method for obtaining magnesium efficiently.

Key concepts

Electrolysis

Electrolysis is a key method used to extract elements like magnesium from their compounds. This process involves passing an electric current through a substance to cause a chemical reaction. When applied to magnesium extraction, the electrolysis process typically involves using a molten or fused magnesium salt.
In this method, positive magnesium ions are attracted to the negatively charged cathode. Here, they gain electrons and are reduced to form elemental magnesium. This technique is favored because it does not require external reacting agents, making it cleaner and more efficient.
Notably, electrolysis of an aqueous magnesium nitrate solution, as in one of the proposed methods, is ineffective for magnesium extraction. This is because water undergoes electrolysis before magnesium ions, leaving behind gases such as oxygen and hydrogen rather than solid magnesium. Utilizing fused salts circumvents this issue.

Metal Reduction

The reduction of metal compounds is a traditional method used to extract metals. However, its application in magnesium extraction is not typically efficient. For instance, using iron to reduce magnesium salt solutions is ineffective because iron does not provide the necessary conditions for reduction.
Similarly, reducing magnesium oxide (BMgOD) with coke, a carbon-rich material, requires extremely high temperatures. Although theoretically possible, this method is energy-intensive and less efficient compared to electrolysis. Thus, while metal reduction is a viable strategy for other metals, it is not the best choice for extracting magnesium.

Chemical Processes

Chemical processes encompass a range of techniques used to alter the composition of substances to extract specific elements. These processes can involve reactions at high temperatures, redox reactions, or the use of chemical reagents.
While magnesium can theoretically be extracted through chemical reduction involving high temperatures or specific reagents, such methods can be complex and resource-intensive. In contrast, electrolysis offers a more straightforward and economical approach.
The choice of chemical process is often based on efficiency and the scale of production, and for magnesium, electrolysis remains the preferred method.

Elemental Magnesium

Elemental magnesium is a valuable and lightweight metal used in various industries such as automotive and aerospace due to its strength and low density. Obtaining magnesium in its pure form requires advanced extraction techniques.
The most widely adopted method is the electrolysis of fused magnesium salts, which efficiently produces high-purity magnesium metal. This process is particularly advantageous for its simplicity and effectiveness, even at a commercial scale.
Understanding the nuances of extracting elemental magnesium is crucial for industries that rely on its unique properties, ensuring sustainable and efficient utilization across various applications.