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) \(\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}\)

Short answer

(a) \(\mathrm{NaCl}\) is used in Down's process.

Step-by-step solution

Understand Down's Process

Down's process is an industrial method for extracting sodium metal from its compounds. It involves the electrolysis of a molten salt mixture to obtain pure sodium.

Identify the Electrolyte Used in Down's Process

In Down's process for extracting sodium, the electrolyte used is molten sodium chloride (\(\mathrm{NaCl}\)). This is because sodium chloride it is easy to melt as it lowers melting point and conductivity compared to pure NaCl.

Verify the Options

We have four options presented: (a) \(\mathrm{NaCl}\)(b) \(\mathrm{NaCl}+\mathrm{NaOH}\)(c) \(\mathrm{NaOH}+\mathrm{KCl}+\mathrm{KF}\)(d) \(\mathrm{NaCl}+\mathrm{KCl}+\mathrm{KF}\)Down's process specifically uses the electrolysis of molten \(\mathrm{NaCl}\) based on industrial practices.

Select the Correct Answer

The correct answer must be option (a) \(\mathrm{NaCl}\) because it is the direct electrolyte used in the Down's process for the extraction of sodium.

Key concepts

Electrolysis

Electrolysis is a chemical process that uses electricity to drive a non-spontaneous reaction. It involves passing an electric current through a substance to induce a chemical change. In the Down's process, electrolysis is crucial since it separates the sodium from other compounds.
This process occurs in an electrolytic cell, a device that accommodates the electrical current needed for the reaction.
To achieve this, ions in the molten substance move towards the electrodes, with cations migrating to the cathode (negative electrode) and anions to the anode (positive electrode). Here is what happens in essence:

• An electric current initiates the movement of ions.
• Cations and anions collect at respective electrodes.
• A chemical reaction occurs at the electrodes.

This results in a separation of sodium metal from the compound, showcasing the function of electrolysis.

Sodium Extraction

The extraction of sodium through Down's process is an example of metal extraction via electrolysis. Sodium is a highly reactive metal that does not naturally occur in its pure form.
Thus, specific methods are required to extract it from its compounds. In Down's process:

• Molten sodium chloride is utilized as the electrolyte.
• Electric current causes sodium ions to migrate towards the cathode.
• Pure sodium metal is collected once the ions are reduced.

This method is favored due to its efficiency in obtaining pure sodium at a large scale.
It capitalizes on the properties of sodium ions and the effectiveness of molten electrolytes in facilitating ion movement and separation.

Molten Sodium Chloride

Molten sodium chloride serves as the electrolyte in Down's process. Heating sodium chloride until it becomes liquid is essential in the context of this process.
This is because the liquid form allows ions to move freely, enabling the electrolysis to proceed effectively and the sodium to be extracted successfully. The benefits of molten sodium chloride include:

• Reduced melting point compared to solid, facilitating easier handling.
• Increased electrical conductivity, which is vital for efficient electrolysis.

By heating NaCl, it transitions from a solid crystalline structure to a liquid state, enabling the free movement of ions.
During Down's process, this results in the separation of pure sodium at the cathode, illustrating its importance in industrial practices.