Despite the fact that the USA sold its helium reserves for airships in 1920, helium shortages do occur from time to time.
While we see helium most often in flying balloons, some scientists are critical of this waste of helium, a resource we have in limited quantities. In fact, helium is one of the most common elements in the universe. It comes right after hydrogen in the prevalence criterion. On the other hand, it is not that common in the world. Because helium is one of the rare elements that can escape from gravity and enter space. While chemist Andrea Sella from the University of London (UCL) stated that it is possible to reuse many gases by recycling, he said that this is not the case for helium.
WHAT IS HELIUM?
It is the lightest gas after hydrogen. Although it is colorless, odorless, it does not react because it is a noble gas, and therefore it is inert. The number of electrons in the last orbits of noble gases is equal to the maximum electron holding capacity of that orbital, that is, the more electrons that orbital can receive, the more electrons it can receive. Helium's atomic number is two (2), as in every element, the maximum electron orbital can take up is two in helium. Accordingly, helium is a gas that complies with the noble gases rule. The relative atomic mass is 4,0026. It is a gas at room temperature, and it is impossible to see it in any other state than a gas under natural conditions; because its melting point is -272,05 °C and boiling point is -268,785 °C. However, it can be seen as solid and liquid at temperatures that can be achieved in laboratory conditions. Since these temperatures are very close to absolute zero, it is very difficult to provide even in laboratory conditions. Its density is 0,1785 g/l, meaning it is lighter than air, so it is used in hot air balloons and zeppelins. It is heavier than hydrogen, but since hydrogen is a flammable substance, it is not used much anymore and is replaced by Helium. Its atomic diameter is 49 pm. It has no electronegativity (electronegativity) and its electron configuration is 1s (square). The number of oxidation digits is zero. (Each 20.000 small helium balloons reduces a person's weight by 6 kg.)
Helium is present in very small amounts in the atmosphere. Also, helium is found in radioactive minerals and natural gases in the United States. Helium is obtained from the fractional distillation of liquid air. Being lighter than air allows it to be used in flying balloons. It is also quite safe since it does not have flammable-explosive properties like hydrogen, but this substance is not used much because this security is expensive. It is expensive because although it is the second most abundant element in the universe after hydrogen and is found at a rate of 1/200.000 in the earth's atmosphere, it cannot be obtained by fractional distillation of liquid air. This is because Helium, unlike many other gases in the atmosphere, is not a positive Joul-Thompson coefficient. This prevents it from being liquefied by compression and makes it impossible to obtain from air. Some natural gas deposits in the USA contain up to 7% He gas, which allows helium to be produced commercially. Helium is used to create an inert atmosphere of some metals due to its inert gas feature. In addition, submersible tubes consist of 80% He and 20% O2. The reason why oxygen mixed with helium is used instead of liquid air is to prevent what is called a profiteering. The function of helium here is that it does not liquefy at high pressure due to the negative Joule-Thompson coefficient mentioned above, and that it does not form bubbles in the blood and cause paralysis due to the solubility difference that occurs in the rapid transition from high pressure to low pressure while the divers ascend upwards. Helium is also used to pressurize liquid rocket fuels. Liquid helium is also used for cooling (in NMR devices)
About helium's refinement of the human voice
This is because sound travels faster through helium. The reason for this is that the speed of sound in gases is inversely proportional to the square root of the density of the gas. Because helium is a much less dense gas than air (like flying balloons), the speed of sound in helium is several times greater than in air. The human voice is high-pitched because the helium vibrates the vocal cords instead of air, and the sound travels faster through helium. This sound attenuation loses its effect after the ingested helium is reintroduced. Similarly, if you inhale SF6 gas, which is inert and non-toxic, this time the human voice is deep, since this gas is about six times denser than air and therefore the sound travels much slower in SF6 than in air.
Source : netgazete
Günceleme: 21/11/2013 00:27