Problem 25 - A Complete Resource Book in Chemistry for JEE Main

Question

Which one of the following electrolysis is used in Down's process of extracting sodium metal? (a) \(\mathrm{NaCl}\) (b) \(\mathrm{NaCl}+\mathrm{NaOH}\) (c) \(\mathrm{NaOH}+\mathrm{KCl}+\mathrm{KF}\) (d) \(\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}\)

Step-by-Step Solution

Answer

(d) \(\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}\) is used in Down's process.

Step 1: Understanding Down's Process

Down's process is an industrial method used to extract sodium metal by the electrolysis of sodium chloride.

Step 2: Identifying the Role of Mixtures in Electrolysis

Mixtures containing sodium chloride are often used in electrolysis to reduce melting point, allow easier melting, or improve efficiency.

Step 3: Analyzing the Options

Evaluate the given options to determine which involves sodium chloride mixed with other chlorides & fluorides, which is a common modification to Down's process to lower melting temperatures.

Step 4: Selecting the Correct Answer

Option (d) \(\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}\) is used in Down's process because the addition of \(\mathrm{KCl}\) and \(\mathrm{KF}\) helps in lowering the melting point of sodium chloride, making it more feasible for electrolysis.

Key Concepts

Electrolysis

Electrolysis is a fascinating process where electricity is used to induce a chemical change, usually separating elements from compounds. In Down's process, electrolysis plays a crucial role. It takes advantage of the fact that sodium can be split from sodium chloride (NaCl) when an electric current is passed through the molten salt. During electrolysis, the electrical energy breaks the ionic bonds between sodium ions (Na\(^+\)) and chloride ions (Cl\(^-\)).

• Saves energy by focusing only on splitting necessary bonds.
• Allows for the extraction of pure sodium, a highly reactive metal.
• Produces chlorine gas as a byproduct, which is also commercially valuable.

Electrolysis is a direct approach to harnessing chemical transformations, making it invaluable not just for sodium extraction but also for other essential industrial processes.

Sodium Extraction

The extraction of sodium from sodium chloride using Down's process is an example of how science and industry work together. The primary goal here is to obtain pure sodium metal which is used in various applications, from street lamps to rocket propellants. This extraction involves placing the sodium chloride in an electrolytic cell, where it's melted down. By allowing an electric current to pass through, sodium is extracted at the cathode, while chlorine gas is released at the anode.

• Sodium is a highly reactive element, especially with water.
• Extracted sodium must be handled with extreme care to prevent accidental reactions.
• Efficient extraction requires controlling temperature and electrical flow carefully.

Down's process highlights the perfect balance between chemistry and engineering, leading to effective sodium extraction.

Sodium Chloride

Sodium chloride, commonly known as table salt, is not just a kitchen staple. In Down's process, NaCl is the primary compound used for extracting sodium. What makes sodium chloride special is its ability to easily transfer into a molten state suitable for electrolysis.

When mixed with other salts like potassium chloride (KCl) and potassium fluoride (KF), the melting point is lowered further, making the process more energy-efficient. Here are crucial points to understand about sodium chloride in this context:

• Essential for breaking down into sodium and chlorine during electrolysis.
• Readily available and relatively inexpensive.
• Serves as a source material for both sodium metal and chlorine gas production.

This compound's role in the process shows its importance not just for daily use but also in large-scale industrial chemistry operations.

Industrial Chemistry

Industrial chemistry is a field where complex chemical processes are adapted for large-scale production. Down's process is a great example of this, showcasing how scientific principles are implemented to produce materials efficiently and economically. In industrial chemistry, the focus is on scaling reactions to produce large amounts of a product. The key benefits include:

• Streamlining production to reduce costs and increase output.
• Developing safe methods for handling and processing reactive elements.
• Producing commercially valuable byproducts like chlorine gas.

By lowering the melting point of the electrolytic mixture, the Down's process improves efficiency—a core aim of industrial chemistry. This ensures that processes are not only technically viable but also economically feasible, driving innovation and availability in the chemical industry.