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Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures.Liquid helium may show superfluidity.. At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (−452.20 °F; 4.15 K).
Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.
The amount of mass that can be lifted by helium in air at sea level is: (1.292 - 0.178) kg/m 3 = 1.114 kg/m 3. and the buoyant force for one m 3 of helium in air at sea level is: 1 m 3 × 1.114 kg/m 3 × 9.8 N/kg= 10.9 N. Thus hydrogen's additional buoyancy compared to helium is: 11.8 / 10.9 ≈ 1.08, or approximately 8.0%
For some usage examples, consider the conversion of 1 SCCM to kg/s of a gas of molecular weight , where is in kg/kmol. Furthermore, consider standard conditions of 101325 Pa and 273.15 K, and assume the gas is an ideal gas (i.e., =).
Helium, 2 He; Helium; Pronunciation / ˈ h iː l i ə m / (HEE-lee-əm) Appearance: colorless gas, exhibiting a gray, cloudy glow (or reddish-orange if an especially high voltage is used) when placed in an electric field: Standard atomic weight A r °(He)
Example: the pie chart for boron shows it to be composed of about 20% 10 B and 80% 11 B. This isotope mix causes the atomic weight of ordinary Earthly boron samples to be expected to fall within the interval 10.806 to 10.821. and this interval is the standard atomic weight. Boron samples from unusual sources, particularly non-terrestrial ...
L. Use of the Terms "Mass" and "Weight" [See Section K. NOTE] When used in this handbook, the term "weight" means "mass". The term "weight" appears when inch-pound units are cited, or when both inch-pound and SI units are included in a requirement. The terms "mass" or "masses" are used when only SI units are cited in a requirement.
Helium is completely non flammable, but gives lower performance-1.02 kg/m 3 (0.064 lb/cu ft) and is a rare element [33] and much more expensive. [34] Thermal airships use a heated lifting gas, usually air, in a fashion similar to hot air balloons. The first to do so was flown in 1973 by the British company Cameron Balloons. [35]