- Chinese
- Search
Acetylene Information
1. Aliases and English Name
- Chinese Aliases: 电石气 (Carbide Gas), 亚次乙基 (Subethylene), 乙叉撑 (Ethyne)
- English Name: Acetylene, Ethyne
---
2. Applications
Acetylene is widely used in:
- Metal welding and cutting
- Organic synthesis
- Atomic absorption spectroscopy
- Standard gas and calibration gas
- Synthetic rubber production
- Illumination
---
3. Production Methods
1. Partial oxidation of methane
2. Hydrolysis of calcium carbide
3. Production from natural gas or liquefied petroleum gas using regenerative thermal decomposition; production from natural gas or methane via partial combustion; production from natural gas or propane via complete combustion; production from hydrocarbons using the electric arc method
---
4. Physical and Chemical Properties
- **InChI**: InChI=1/C2H2/c1-2/h1-2H
- **Molecular Formula**: C₂H₂
- **Molecular Weight**: 26.04
- **Bond Angle**: 180°
- **Molecular Configuration**: Linear
- **Hybridization**: sp hybridization
- **Lone Pairs on Central Atom**: 0
- **Common Units**: m³, mm³, cm³
- **Density**: 1.17 kg/m³ under standard pressure; 1.12 kg/m³ at 25°C
- **Melting Point**: -84°C
- **Boiling Point**: -80.8°C
- **Hazard Symbol**: 4 (Flammable Gas)
- **Packaging**: Steel cylinders
**Description**:
Acetylene is a colorless, flammable gas with narcotic properties under normal temperature and pressure. Pure acetylene is odorless, but impurities give it an unpleasant garlic-like smell. It is lighter than air, capable of forming explosive mixtures with air, and is highly combustible and explosive. It is slightly soluble in water (0.94 cm³/cm³ at 25°C and 101.325 kPa), and dissolves well in alcohol, acetone, and ether. At 15°C and 1 atm, one volume of acetone can dissolve 25 volumes of acetylene; at 12 atm, it can dissolve 300 volumes. Acetylene forms explosive compounds with mercury, silver, and copper, and reacts explosively with fluorine and chlorine. Under high pressure, acetylene is highly unstable—sparks, heat, or friction can trigger explosive decomposition into hydrogen and carbon. To stabilize it under pressure, acetylene is typically dissolved in acetone. In production and usage pipelines, acetylene pressure is generally kept below 1 atm gauge pressure.
---
5. Toxicity
- **Maximum Allowable Concentration**: 1000 ppm
Acetylene itself is non-toxic but can cause asphyxiation at high concentrations. Mixtures with oxygen exhibit narcotic effects. Symptoms of acetylene inhalation include dizziness, headache, nausea, cyanosis, central nervous system stimulation, coma, collapse, and, in severe cases, death by asphyxiation.
---
6. Safety Precautions
- **Storage**: Acetylene is typically dissolved in solvents like acetone and porous materials, stored in steel cylinders. Cylinders should be kept in a cool, dry, well-ventilated area with storage temperatures not exceeding 30°C, ideally isolated outdoors. Keep away from ignition sources, heat, direct sunlight, oxygen, compressed air, oxidants, fluorine, chlorine, bromine, copper, silver, mercury, copper salts, mercury salts, silver salts, organic peroxides, explosives, toxic substances, and radioactive materials. Equipment and pipelines should be grounded and tightly sealed, with leaks detectable using surfactant solutions.
- **Safe Storage and Transport**: Currently, the only safe method is dissolved acetylene. Acetylene is highly unstable under pressure, releasing significant heat during decomposition, and poses an explosion risk in the presence of catalysts (e.g., copper forms explosive copper acetylide) or when mixed with air over a wide explosive range. Dissolving pressurized acetylene in acetone-soaked porous materials ensures safety. Even if a portion ignites, the reaction does not spread, maintaining overall safety. However, this safety depends on purity: acetylene must be >98.0% pure, with no more than 2% oxygen-supporting gases and no hydrogen sulfide or phosphine.
- **Material Compatibility**:
- Acetylene is non-corrosive and compatible with most metals, but copper, silver, and mercury must not be used. Avoid brass with >66% copper, copper-silver solder, and mercury-containing pressure gauges.
- Compatible materials include cellulose acetate, nylon, phenol formaldehyde, phenol furfural, polypropylene, polyurethane, polyvinyl chloride (PVC), PVC acetate, polychlorotrifluoroethylene, polytetrafluoroethylene, epoxy resin, phenolic polymer, natural rubber, nitrile rubber, styrene-butadiene rubber, and butyl rubber.
- **Firefighting**: Use water mist or carbon dioxide in case of fire.
- **Leak Handling**: Use forced ventilation to reduce concentration below explosive limits. Transfer leaking containers to an open area for slow release into the atmosphere, direct into a combustion furnace via tubing, or carefully burn off in a low-lying area.