Ethyne Production & Properties | Chemistry for JAMB PDF Download

Introduction

Alkynes are a class of organic compounds characterized by the presence of a triple bond between carbon atoms. Ethyne, commonly known as acetylene, is the simplest alkyne and has the chemical formula C₂H₂. In this note, we will discuss the production of ethyne from the action of water on carbides, as well as explore some of its simple reactions and properties.

Production of Ethyne from the Action of Water on Carbides

• Ethyne can be produced by the action of water on carbides, such as calcium carbide (CaC₂) or magnesium carbide (Mg₂C).
• The reaction is represented by the following equation: CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂.
• The carbide is treated with water, resulting in the release of ethyne gas.

Simple Reactions of Ethyne

• Combustion: Ethyne readily undergoes combustion in the presence of oxygen. The reaction is highly exothermic and produces carbon dioxide (CO₂) and water (H₂O). The balanced equation is: 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O.
• Addition Reactions: Ethyne can undergo addition reactions with halogens (e.g., Cl₂, Br₂) to form dihalogenated products. For example, ethyne reacts with chlorine gas to produce 1,1,2,2-tetrachloroethane.
• Polymerization: Ethyne can undergo polymerization to form long-chain hydrocarbons, such as polyacetylene. This reaction involves the repeated addition of ethyne molecules to form a polymer chain.

Properties of Ethyne

• Physical State: Ethyne is a colorless gas at room temperature and pressure.
• Odor: It has a distinct odor, which can be detected at low concentrations.
• Solubility: Ethyne is sparingly soluble in water but is soluble in organic solvents, such as benzene or hexane.
• Density: Ethyne is lighter than air, with a density of approximately 0.91 g/L.
• Stability: Ethyne is a relatively unstable compound and can decompose explosively under certain conditions.

Conclusion

Ethyne, or acetylene, is an important alkyne with various applications in industry and chemistry. It can be produced by the action of water on carbides and exhibits characteristic reactions, including combustion, addition reactions, and polymerization. Understanding the production, reactions, and properties of ethyne is crucial in the study of organic chemistry.