Physical and chemical properties of acetylene

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Acetylene C2H2 1. Aliases/English names: carbide gas, ethylidene, ethynylene； Acetylene, Ethyne. 2. Uses: Welding and cutting of metals, organic synthesis, atomic absorption spectroscopy, standard gases, calibration gases, synthetic rubber, lighting. 3. Production method (1) Partial oxidation of methane. (2) Hydrolysis of calcium carbide. (3) Produced using natural gas and liquefied petroleum gas as raw materials through a regenerative thermal decomposition method. It is produced by partial combustion using natural gas or methane as raw material. Produced by complete combustion using natural gas or propane as raw materials. Produced by the arc method using hydrocarbons as raw materials ( ). 4. Physical and chemical properties
Molecular weight: 26.038
Triple point: (128 kPa): –80.55°C
Boiling point (170 kPa): –75.0°C
Liquid density (–80.75°C): 610 kg/m³
Gas density (273.15 K, 101.325 kPa): 1.1747 kg/m³
Relative density (air = 1, 0°C, 101.325 kPa): 0.908
Specific volume (15.6°C, 101.325 kPa): 0.9008 m³/kg
Volume ratio of gas to liquid (15°C, 100 kPa): 556 L/L
Critical temperature: 3532°C
Critical pressure: 6190 kPa
Critical density: 230.4 kg/m³
Compressibility coefficient:
Temperature (K), Pressure (kPa):
50.66, 101.33; 50.66, 1013.25; 290, 3200; 0.9985; 0.9969; 0.9927; 0.9941; 0.9601; 0.9708; 0.9184; 0.9405
Heat of fusion (–80.75°C, 128 kPa): 96.4 kJ/kg
Heat of vaporization (–83.80°C, 101.325 kPa): 801.36 kJ/kg
Specific heat capacities (0°C, 101.33 kPa):
Cp = 1636.62 J/(kg·K), Cv = 1308.79 J/(kg·K)
Specific heat ratio (26.8°C, 101.325 kPa): Cp/Cv = 1.234
Vapor pressure:
–20°C: 1510 kPa; 0°C: 2665 kPa; 20°C: 4367 kPa
Viscosity (101.33 kPa, 20°C): 0.0103 mPa·s
Thermal conductivity (101.325 kPa, 200 K): 0.01181 W/(m·K)
Refractive index (20°C, 101.325 kPa, 5876 Å, gas): n = 1.000598
Flammability range in air (20°C, 101.325 kPa): 2.2%–85%
Minimum auto-ignition temperature in air (101.325 kPa): 305°C
Flame temperature during equivalent combustion in air: 2950°C
Maximum flame velocity during equivalent combustion in air: 1.46 m/s
Flammability range in oxygen (20°C, 101.325 kPa): 2.8%–93%
Minimum auto-ignition temperature in oxygen (101.325 kPa): 296°C
Flame temperature during equivalent combustion in oxygen: 3070°C
Maximum flame velocity during equivalent combustion in oxygen: 7.60 m/s
Heat of combustion during equivalent combustion in oxygen: 58492 J/m³ (upper limit), 56442 J/m³ (lower limit)
Concentration producing maximum explosion pressure in air: 14.5%
Maximum explosion pressure: 10.3 kg/cm³
Minimum ignition energy: 0.019 mJ
Toxicity level: 1
Flammability level: 4
Explosivity level: 3
Acetylene is a colorless, flammable gas that is ** at normal temperature and pressure. Pure time has no odor, but it has an unpleasant garlic smell when impurities are present. Lighter than air, it can form explosive mixtures with air, and is highly flammable and explosive. Slightly soluble in water; at 25°C and 101.325 kPa, its solubility in water is 0.94 cm3/cm3. Soluble in alcohol, acetone, benzene, ether, etc. At 15°C and 1 atmosphere of pressure, one volume of propane can dissolve 25 volumes of acetylene, while at 12 atmospheres of pressure, it can dissolve 300 volumes of acetylene. It forms explosive compounds when combined with mercury, silver, copper, and others. It can undergo explosive reactions with fluorine and chlorine. Acetylene is very unstable under high pressure; sparks, heat, and friction can all cause its explosive decomposition to produce hydrogen and carbon. Therefore, acetylene must be dissolved in propane to remain stable at high pressures. Generally, the pressure of acetylene in the pipes for its generation and use is kept below 1 atmosphere of gauge pressure. The hazards associated with the mixing and contact of acetylene with certain substances are shown in the table below. Names of hazardous substances in mixed contact, chemical formulas, hazard levels, and summaries: Copper, Silver, Cobalt, Potassium; Rubidium hydride, Sodium hydride, Mercury, Copper carbide, Iodine, Chlorine, Silver nitrate, Mercury nitrate, Trifluoromethyl hypofluoric acid, Cesium hydride. CuAgCoK, RbHNa, HHg, Cu2C2I2, Cl2, AgNO3, Hg(NO3)2, CF4, OCsH. AAAAAAAAAA. There is a possibility of the formation of explosive substances. There is a possibility of the formation of explosive substances. There is a risk of decomposition and polymerization. There is a risk of fire and explosion. Depending on conditions, there is a possibility of intense reactions. Depending on conditions, there is a possibility of intense reactions. There is a possibility of the formation of ** certain substances. Heating or impact can lead to explosion hazards. There are explosion hazards. Depending on conditions, there is a possibility of explosion. There is a possibility of the formation of explosive substances. There is a possibility of the formation of explosive substances. There is a risk of explosive reactions. Depending on conditions, there is a possibility of intense reactions. 5. Toxicity: Maximum allowable concentration: 1000 ppm. Acetylene itself is non-toxic, but it can cause asphyxiation at high concentrations. A mixture of acetylene and oxygen has a **effect**. Symptoms that occur after inhaling acetylene gas include dizziness, headache, nausea, cyanosis, irritation of the central nervous system, coma, and collapse; in severe cases, it can lead to death from asphyxiation. 6. Safety protection: Acetylene is usually dissolved in solvents such as propane as well as in porous materials, and then placed in steel cylinders. These cylinders should be stored in a cool, well-ventilated, and dry place, with the storage temperature not exceeding 30°C. It is best to store it separately outdoors in isolation. Keep away from sources of fire and heat, and avoid direct sunlight. It should be separated from oxygen, compressed air, oxidizers, fluorine, chlorine, bromine, copper, silver, mercury, copper salts, mercury salts, silver salts, organic peroxides, **, poisons, radioactive materials, etc. The equipment pipes should be grounded and tightly sealed. Leak detection can be done using a surfactant solution. For the safe storage and transportation of acetylene gas, the only current method is dissolved acetylene. Because acetylene is very unstable, it can decompose on its own under pressure, releasing a large amount of heat ； Or there is a risk of explosion in the presence of a catalytic substance (which reacts with copper to form an explosive compound, copper acetylide) ； It has a wide explosive range when mixed with air. However, it is very safe to pressurize acetylene gas and dissolve it in a porous material that has been soaked in propane. Even if a part causes burning or something similar, it will not spread to other parts, so the whole remains safe. However, this safety is closely related to the purity of acetylene. The purity of acetylene gas must be greater than 98.0%; it is not allowed to contain more than 2% of oxidizing gases, nor hydrogen sulfide or phosphine. Acetylene is a non-corrosive gas, so ordinary metal materials can be used, but copper, silver, and mercury cannot. Avoid using brass with more than 66% copper content, copper-silver welding materials, and mercury-containing pressure gauges. Acetate fiber, nylon, phenol-formaldehyde, phenol-furfural, polypropylene, polyurethane, polyvinyl chloride, polyvinyl chloride acetate, polychlorotrifluoroethylene, polytetrafluoroethylene, epoxy resin, and phenol oligomer polymers can be used. Natural rubber, nitrile rubber, styrene-butadiene rubber, and butyl rubber can also be used. In case of a fire, fog water and carbon dioxide can be used for extinguishing it. When there is a leak, use forced ventilation to keep the concentration below the explosive level. The container with the leak can be moved to an open area where it can leak slowly into the atmosphere, or it can be fed into a combustion furnace via a pipe, or carefully ignited and burned in a depression.