【Daily Question】Chemical Analysis Version, 2021.8.12
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When calcium carbide or acetylene, which are used as chemical raw materials, catch fire, it is strictly prohibited to use ( ) to extinguish the fire. A. CO2 fire extinguisher B. Carbon tetrachloride fire extinguisher C. Dry powder fire extinguisher D. Dry sand B
This post was last edited by yyszyj on 2021-8-12 08:44: A. CO2 fire extinguishers. B committed the crime yesterday, but I still insist on choosing A. Water must not be used to extinguish a fire caused by calcium carbide, as its main component is CaC2, that is, calcium carbide itself. Calcium carbide reacts with water to produce acetylene gas, which causes the fire to grow larger. The main component of calcium carbide is CaC2, which reacts violently with the water produced by carbon dioxide foam extinguishers, resulting in the formation of acetylene: CaC2 + 2H2O → Ca(OH)2 + CH≡CH↑, along with the release of heat. The formation of acetylene can lead to explosions. At high temperatures, the combination of chlorine and acetylene can cause an explosion; in addition, the highly toxic gas phosgene is produced. Carbon tetrachloride was once used as a fire extinguishing agent, but it was discontinued because it reacts with water at temperatures above 500 degrees Celsius to produce carbon dioxide and toxic gases such as phosgene, chlorine, and hydrogen chloride. Additionally, it accelerates the breakdown of the ozone layer.
Carbon dioxide extinguishants and carbon dioxide foam extinguishants are two different things.