CHEMICAL AND PHYSICAL PROPERTIES
| Physical Description | Helium appears as a colorless, odorless, noncombustible gas. Can asphyxiate. Inhalation causes the voice to become squeaky (Mickey Mouse voice). Exposure of the container to prolonged heat or fire can cause it to rupture violently and rocket. If liquefied, contact of the very cold liquid with water causes violent boiling. Pressures may build to dangerous levels if the liquid contacts water in a closed container. Used in arc welding, to trace leaks in refrigeration and other closed systems and as a lifting gas for lighter-than-air aircraft. |
|---|---|
| Color/Form | Colorless gas |
| Odor | Odorless |
| Taste | Tasteless |
| Boiling Point | -269 |
| Melting Point | -272.2 |
| Solubility | 1.5mg/L |
| Density | 1.64 g/L |
| Vapor Density | Relative vapor density (air = 1): 0.14 |
| LogP | 0.28 |
| Stability/Shelf Life | Chemical stability: Stable under recommended storage conditions. |
| Viscosity | 1.953 at 20 °C, 0.1 MPa; 1.977 at 20 °C, 20 MPa |
| Heat of Combustion | 0.0 J/kmol |
| Other Experimental Properties | Naturally occurring isotopes: He-3; He-4. Isotopes: He-5; He-6; He-7; He-8; He-9; He-10 Table: Decay Pathways [Table#1637] |
| Chemical Classes | Toxic Gases & Vapors -> Simple Asphyxiants |
SAFETY INFORMATION
| Signal word | Warning |
|---|---|
| Pictogram(s) |
 Gas Cylinder Compressed Gases GHS04 |
| GHS Hazard Statements |
H280:Gases under pressure |
| Precautionary Statement Codes |
P410+P403:Protect from sunlight. Store in a well-ventilated place. |
COMPUTED DESCRIPTORS
| Molecular Weight | 4.00260 g/mol |
|---|---|
| Hydrogen Bond Donor Count | 0 |
| Hydrogen Bond Acceptor Count | 0 |
| Rotatable Bond Count | 0 |
| Exact Mass | 4.002603254 g/mol |
| Monoisotopic Mass | 4.002603254 g/mol |
| Topological Polar Surface Area | 0 Ų |
| Heavy Atom Count | 1 |
| Formal Charge | 0 |
| Complexity | 0 |
| Isotope Atom Count | 0 |
| Defined Atom Stereocenter Count | 0 |
| Undefined Atom Stereocenter Count | 0 |
| Defined Bond Stereocenter Count | 0 |
| Undefined Bond Stereocenter Count | 0 |
| Covalently-Bonded Unit Count | 1 |
| Compound Is Canonicalized | Yes |
PRODUCT INTRODUCTION
description
Helium appears as a colorless, odorless, noncombustible gas. Can asphyxiate. Inhalation causes the voice to become squeaky (Mickey Mouse voice). Exposure of the container to prolonged heat or fire can cause it to rupture violently and rocket. If liquefied, contact of the very cold liquid with water causes violent boiling. Pressures may build to dangerous levels if the liquid contacts water in a closed container. Used in arc welding, to trace leaks in refrigeration and other closed systems and as a lifting gas for lighter-than-air aircraft.