| Physical Description |
Acetylene appears as a colorless gas with a faint garlic-like odor. Easily ignited and burns with a sooty flame. Gas is lighter than air. Flame may flash back to the source of a leak very easily. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. |
| Color/Form |
Colorless gas ... [Note: Shipped under pressure dissolved in acetone] |
| Odor |
Not unpleasant odor unless impure (due to phosphine) |
| Boiling Point |
-119 °F at 760 mmHg (USCG, 1999) |
| Melting Point |
-119 °F (Sublimes) (NIOSH, 2023) |
| Flash Point |
0 °F |
| Solubility |
2 % (NIOSH, 2023) |
| Density |
0.613 at -112 °F (USCG, 1999) - Less dense than water; will float |
| Vapor Density |
0.91 (NIOSH, 2023) - Lighter than air; will rise (Relative to Air) |
| Vapor Pressure |
44.2 atm (NIOSH, 2023) |
| LogP |
log Kow = 0.37 |
| Stability/Shelf Life |
Stability during transport: Stable as shipped. |
| Autoignition Temperature |
581 °F (USCG, 1999) |
| Decomposition |
/Acetylene/, the extremely endothermic gas ... may decomposed explosively in absence of air ... /and/ readily escalates to detonation in tubular vessels. This type of explosive decomposition has been experienced in a 7 mile acetylene pipeline system ... Accidental local heating to 185 °C or above of part of the wall (as little as 6 sq cm may be enough) of a cylinder containing acetylene may lead to the development of an extremely dangerous situation. At this temperature, exothermic and self-sustaining decomposition of (endothermic) acetylene may set in, and if not stopped by rapid and effective cooling (large volume water spray), the cylinder may explode without warning. Flame flash-back into a cylinder from a wrongly adjusted and/or damaged welding or cutting torch can cause the same effect ... |
| Heat of Combustion |
313 cal |
| Ionization Potential |
11.40 eV |
| Polymerization |
The heating of acetylene may lead to polymerization reactions which are highly exothermic. |
| Odor Threshold |
Odor Threshold Low: 226.0 [ppm] Odor Threshold High: 2584.0 [ppm] Odor threshold from AIHA |
| Refractive Index |
INDEX OF REFRACTION: 1.00051 @ 0 °C/D |
| Kovats Retention Index |
195 182 156 176 155 165 165 |
| Other Experimental Properties |
Air pollution factors: 1 mg/cu m = 0.92 ppm; 1 ppm = 1.08 mg/cu m |
| Chemical Classes |
Toxic Gases & Vapors -> Simple Asphyxiants |
