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Introduction to carbon dioxide used in the production of electric light sources
Carbon dioxide is commonly known as carbonic acid gas. It is a colorless and odorless gas with a slightly sour taste. Under standard conditions, its density is 1.977g/L. It dissolves in water and partially forms carbonic acid (H:COs). 002 has very stable chemical properties and can be liquefied into a colorless liquid at 20℃ and 5.5x10Pa pressure.
When liquid carbon dioxide evaporates, it can absorb a large amount of heat and condense into white snow-like solid carbon dioxide, commonly known as dry ice. Dry ice sublimates at -78.5℃ under normal pressure. The critical temperature is 31.0℃ and the critical pressure is 7.4x10Pa.
Carbon dioxide can be obtained by burning carbon in excess air, or by calcining marble, limestone, and dolomite or reacting with acid.
In the production of electric light sources, dry ice is often used as a refrigerant for cold traps in vacuum systems to prevent oil vapor and water vapor from entering the lamp tube to be pumped; in the process of manufacturing iodine tungsten lamps, it is also often used to freeze iodine and control the amount of iodine filling. Due to its inactive chemical properties, carbon dioxide is also used as a protective gas.