Calcium carbide

Chemical compound used in industry and agriculture

Calcium Carbide

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Calcium carbide in its raw form

Calcium carbide is a chemical compound with the chemical formula CaC_. It is a colorless solid at room temperature, although it is often encountered as a gray or brown powder due to impurities. Calcium carbide is primarily used in the production of acetylene gas and in the manufacture of calcium cyanamide.

Chemical Properties

Calcium carbide is a compound of calcium and carbon. It is produced industrially in an electric arc furnace from a mixture of lime (CaO) and coke at approximately 2,200 °C (3,990 °F). The reaction is as follows:

CaO + 3C _ CaC_ + CO

The resulting calcium carbide is then cooled and ground into a powder. When calcium carbide comes into contact with water, it reacts to produce acetylene gas and calcium hydroxide:

CaC_ + 2H_O _ C_H_ + Ca(OH)_

This reaction is highly exothermic and is the basis for its use in acetylene production.

Uses

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A miner's lamp using acetylene gas

The primary use of calcium carbide is in the production of acetylene gas, which is used as a fuel and a chemical building block. Acetylene is used in welding and cutting metals, as well as in the synthesis of various organic chemicals.

Calcium carbide is also used in the manufacture of calcium cyanamide, a fertilizer and herbicide. The reaction with nitrogen gas produces calcium cyanamide:

CaC_ + N_ _ CaCN_ + C

In addition, calcium carbide is used in the desulfurization of iron and steel, as it can remove sulfur impurities from molten metal.

Safety and Handling

Calcium carbide is a hazardous material and must be handled with care. It reacts violently with water, releasing flammable acetylene gas, which can form explosive mixtures with air. Proper storage and handling procedures must be followed to prevent accidental contact with moisture.

Historical Context

Calcium carbide was first discovered in 1836 by the German chemist Friedrich Wöhler. Its industrial production began in the late 19th century, and it played a significant role in the development of the acetylene industry. The use of acetylene lamps was widespread in the early 20th century, particularly in mining and caving.

Related Pages

• Acetylene
• Calcium cyanamide
• Electric arc furnace
• Desulfurization