⚠️ Warnings
Xenon gas can be safely kept in normal sealed glass or metal containers atstandard temperature and pressure. However, it readily dissolves in most plastics and rubber, and will gradually escape from a container sealed with such materials.Xenon is non-toxic, although it does dissolve in blood and belongs to a select group of substances that penetrate theblood–brain barrier, causing mild to full surgicalanesthesiawhen inhaled in high concentrations with oxygen.
Thespeed of soundin xenon gas (169 m/s) is less than that in airbecause the average velocity of the heavy xenon atoms is less than that of nitrogen and oxygen molecules in air. Hence, xenon vibrates more slowly in thevocal cordswhen exhaled and produces lowered voice tones (low-frequency-enhanced sounds, but thefundamental frequencyorpitchdoes not change), an effect opposite to the high-toned voice produced inhelium. Specifically, when thevocal tractis filled with xenon gas, its natural resonant frequency becomes lower than when it is filled with air. Thus, the low frequencies of the sound wave produced by the same direct vibration of thevocal cordswould be enhanced, resulting in a change of thetimbreof the sound amplified by the vocal tract. Like helium, xenon does not satisfy the body's need for oxygen, and it is both a simpleasphyxiantand an anesthetic more powerful than nitrous oxide; consequently, and because xenon is expensive, many universities have prohibited the voice stunt as a general chemistry demonstration.The gassulfur hexafluorideis similar to xenon in molecular weight (146 versus 131), less expensive, and though an asphyxiant, not toxic or anesthetic; it is often substituted in these demonstrations.
Dense gases such as xenon and sulfur hexafluoride can be breathed safely when mixed with at least 20% oxygen. Xenon at 80% concentration along with 20% oxygen rapidly produces the unconsciousness of general anesthesia. Breathing mixes gases of different densities very effectively and rapidly so that heavier gases are purged along with the oxygen, and do not accumulate at the bottom of the lungs.There is, however, a danger associated with any heavy gas in large quantities: it may sit invisibly in a container, and a person who enters an area filled with an odorless, colorless gas may be asphyxiated without warning. Xenon is rarely used in large enough quantities for this to be a concern, though the potential for danger exists any time a tank or container of xenon is kept in an unventilated space.
Water-soluble xenon compounds such asmonosodium xenateare moderately toxic, but have a very short half-life in the body –intravenouslyinjected xenate is reduced to elemental xenon in about a minute.
