Introduction:
When an electrode is not allowed to take part in the chemical reaction, it means that it should remain inert and not undergo any oxidation or reduction during the reaction. In such cases, graphite is the preferred electrode due to its unique properties.

Properties of graphite:
1. Inertness: Graphite is a form of carbon that is highly inert and does not react with most chemicals. It remains stable even under harsh conditions, which makes it an ideal choice for electrodes in various electrochemical processes.

2. High electrical conductivity: Graphite has a high electrical conductivity, which allows for efficient electron transfer during the electrochemical reactions. This property is essential for electrodes as it ensures a good flow of electrical current.

3. Chemical stability: Graphite is chemically stable and does not easily corrode or degrade in the presence of electrolytes. It can withstand the corrosive nature of many substances, making it suitable for use in various electrochemical processes.

4. Large surface area: Graphite electrodes often have a large surface area, which provides more active sites for the electrochemical reactions to occur. This enhances the efficiency and effectiveness of the electrode.

Advantages of using graphite electrodes:
- Graphite electrodes are cost-effective compared to other materials like gold, silver, or platinum.
- They have a longer lifespan and do not require frequent replacement.
- Graphite electrodes are readily available in various sizes and shapes, making them versatile for different applications.
- They have a wide range of operating temperatures and can withstand high temperatures without significant degradation.

Applications:
Graphite electrodes find extensive use in various industries and processes, including:
- Electrolysis: Graphite electrodes are commonly used in electrolytic cells, where they facilitate the production of various chemicals and metals through electrolysis.
- Batteries: Graphite serves as an electrode material in many types of batteries, including lithium-ion batteries, due to its high electrical conductivity and stability.
- Electroplating: Graphite electrodes are used in electroplating processes to deposit a layer of metal onto a substrate.
- Fuel cells: Graphite electrodes play a crucial role in fuel cells, where they facilitate the conversion of chemical energy into electrical energy.

In conclusion, graphite is the preferred electrode when it is not allowed to take part in the chemical reaction due to its inertness, high conductivity, chemical stability, and large surface area. These properties make graphite electrodes suitable for a wide range of applications in various industries.