Electrolysis of salts of highly reactive metals to obtain metal is known as electrolytic reduction.

Electrolytic Reduction:
Electrolytic reduction is a process in which a compound is reduced using electricity. It involves the passing of an electric current through a molten or dissolved compound, causing the reduction of the compound's ions to produce a metal or other reduced form.

Obtaining Sodium from Molten Sodium Chloride:
Sodium is obtained from its molten chloride through the process of electrolytic reduction. This process is commonly known as the Downs process, named after its inventor, Humphry Davy.

The process involves the following steps:

1. Preparation of Molten Sodium Chloride:
Sodium chloride (NaCl) is heated to a high temperature until it melts, forming a molten state. This is typically done by using a high-temperature furnace.

2. Electrolysis Cell Setup:
An electrolysis cell is set up with two electrodes: a cathode and an anode. The cathode is typically made of a material that can withstand high temperatures, such as iron, while the anode is usually made of graphite.

3. Electrolyte Composition:
The molten sodium chloride acts as the electrolyte in the cell. It dissociates into sodium ions (Na+) and chloride ions (Cl-) due to the high temperature.

4. Electrolysis Process:
When an electric current is passed through the electrolyte, positive sodium ions migrate towards the cathode (negative electrode), while negative chloride ions move towards the anode (positive electrode).

5. Reduction at the Cathode:
At the cathode, sodium ions gain electrons from the electrode and are reduced to form sodium atoms. This occurs due to the attraction of positive sodium ions to the negatively charged cathode.

6. Oxidation at the Anode:
At the anode, chloride ions lose electrons and are oxidized to form chlorine gas. This occurs due to the release of negative chloride ions towards the positively charged anode.

7. Collection of Sodium:
As sodium atoms are formed at the cathode, they are denser than the molten sodium chloride and sink to the bottom of the electrolysis cell. Sodium is collected by periodically draining it from the cell.

8. Chlorine Gas Separation:
The chlorine gas produced at the anode is collected separately by various methods, such as bubbling it through water to dissolve it as hydrochloric acid or using a gas collection system.

9. Overall Reaction:
The overall reaction during the electrolysis of molten sodium chloride can be represented as:
2NaCl(l) → 2Na(l) + Cl2(g)

Conclusion:
Electrolytic reduction is a key process in obtaining sodium from molten sodium chloride. Through the application of an electric current, the positive sodium ions are reduced at the cathode to form sodium atoms, while the negative chloride ions are oxidized at the anode to produce chlorine gas. This process allows for the extraction of sodium, which can then be collected and used for various applications.