Containers helium

Natural gas may contain helium, hydrogen and mercury, though the latter is rarely a significant contaminant in small quantities. 

The yellow balloon contains helium (MM = 4.003 g/mol) and has a lower density than air at the same temperature and pressure. 

Equation (105) is much more restrictive than Eq. (104) Eq. (105) is obeyed only by those systems having highly dissimilar components, e.g., systems containing helium. 

C05-0103. The figure shows three chambers with equal volumes, all at the same temperature, connected by closed valves. Each chamber contains helium gas, with amounts proportional to the number of atoms shown. 

The mechanical supports of the tank containing helium, are made of low-conductivity materials such as stainless steal or fibreglass. Sometimes a double system of supports is used strong supports (fairly conductive) which stand the high launch accelerations (up to 30 g) are added which are eliminated when the satellite is in orbit in the absence of gravity. 

In 1907 Lord Rayleigh showed that many rocks, such as Matopo granite and syenite from Mt Sorrel in Leicestershire and from Norway, which contain helium also contain argon (68). 

In 1881 L. Palmieri thought he detected helium in a yellow amorphous sublimation product from Vesuvius. When he heated it in the Bunsen flame, he was able to observe the D3 spectroscopic line with a wave length of 5875 Angstrom units (69, TO). Although R. Nasini and F. Anderlini were unable in 1906 to produce this line by similarly heating minerals known to contain helium, they believed that, if the helium in Palmieri s mineral was bound endothermally, he might possibly have observed its spectrum in this manner (69, 71). 

Because it is the lightest known gas, hydrogen was once used to float airships and aeronautical balloons. But it happens to be also extremely dangerous, and will burn readily (sometimes explosively) in oxygen. After a couple of spectacular disasters, the idea of passenger airships was abandoned in favor of airliners. Today, gas-filled balloons (often used for weather surveys) contain helium, which is also light, and safer than hydrogen. 

Samarskite occurs in the Ural Mountains, Mitchell County (North Carolina, U.S.A.), Canada, and India. The tantalum content is often small, sometimes nil, and the rare earth oxides, chiefly yttria and ceria, are usually present in considerable number and proportions. The ore is radioactive and contains helium. It forms black, orthorhombic crystals. The density varies from 4-2 to G-2.5 It has been suggested that the niobium and tantalum are disintegration products of compounds of yttrium and cerium with the two higher homologues of manganese,4 masurium, and rhenium. 

H-H and the H-H+ potential curves are only negligibly perturbed by He and He, respectively. This means, of course, that no reactions in which reactions products containing helium are formed occur prior to the ionization. On the other hand, it is found in mass-spectrometric studies that, in addition to H2+, the products HeH and HeH+ are formed.9,87,88 These products can only arise from reactions, in the second half of the (Pl)-colli-sion, between the vibrationally excited H and He. We may indicate these conditions by the following scheme ... 

From this point of view, all the dependencies are explained naturally in a series of mixtures containing helium, oxygen or nitrogen, and bromine, the diffusion coefficient of the hydrogen falls from the first to the last, but the thermal diffusivity falls even more sharply, 0/n grows and, therefore, the... 

A 250-mL flask contained krypton at 500 torr. A 450-mL flask contained helium at 950 torr. The contents of the two flasks were mixed by opening a stopcock connecting them. Assuming that all operations were carried out at a constant temperature, calculate the final pressure and the volume percent of each gas in the mixture. Neglect the volume of the stopcock. 

The other main attribute of aluminosilicate glass is it s ability to contain helium. Most glass containers cannot contain helium for extended periods of time, because the small atoms leak past the glass molecular network. Aluminosilicate glass is considered helium leakproof and is used to contain helium for long periods in a laboratory glass system. 

Aluminosilicates are used for ignition tubes, for halogen lamps, and for containing helium. h Vycor is 96% silica glass. 

Because no vacuum system can be truly leak-free, it is important to determine whether or not you have a leak of consequence. In other words, does any system leak actively affect your work For example, a common rubber balloon holds water better than it holds air, and it holds air better than it holds helium. If your needs are to contain water, a standard rubber balloon is sufficient. Similarly, if you want to contain helium for a limited time, again a rubber balloon is sufficient. However, if you want a helium balloon to stay up for several days, then a rubber balloon is insufficient and you must spend the money for a Mylar balloon, which can contain helium much better than a rubber balloon. 

Water has a high helium dissolution capacity, and groundwaters in nature contain helium in a concentration range spanning over five orders of magnitude, as seen in Table 14.1. In all these cases the partial helium pressure in the aquifers was orders of magnitude below the hydrostatic pressure, not to mention the lithostatic pressure, ensuring no gas losses took place. 

An enclosure contains helium at a pressure of 1.3 atm and has two vertical heating surfaces, which are maintained at 80 and 20JC, respectively. The vertical surfaces are 40 by 40 cm and are separated by a gap of 2.0 cm. Calculate the free-convection heat transfer between the vertical surfaces. 

A weather balloon containing helium is released into the atmosphere. As it rises, atmospheric pressure and temperature both decrease. Explain why the size of the balloon increases. 

Small amounts of helium are extracted from the atmosphere by fractionation methods, but not commercially because of the small amount of helium in the atmosphere. A number of natural gas wells contain helium, which can be recovered by a liquefaction and stripping process. Natural gas containing at least 0.2 percent helium has been found in the American Southwest, where the natural gas fields are the major U.S. source of helium. Those helium-rich fields are within 250 miles of Amarillo, Texas other helium-bearing fields have been found in Saskatchewan, Canada, and in areas near the Black Sea. Helium cannot be synthesized so conservation and cleanup recycle systems for spent gas are important means of preserving the earth s helium resources. 

NMR chemical shifts of the appropriate endohedral fullerenes (fullerenes that contain helium atoms)... 

A spherical glass container of unknown volume contains helium gas at 25°C and 1.960 atm. When a portion of the helium is withdrawn and adjusted to 1.00 atm at 25°C, it is found to have a volume of 1.75 cm3. The gas remaining in the first container shows a pressure of 1.710 atm. Calculate the volume of the spherical container. 

A scientific supply house markets aerosol-type cans containing compressed helium for filling balloons, doing demonstrations, and the like. On the label there appears the notice Because the can contains helium, it quite naturally feels empty. It is actually lighter full than empty. ... 

What is the total pressure of a gaseous mixture containing helium, oxygen, and carbon dioxide, if the partial pressure exerted by each gas is 25.0 kPa ... 

The most important source of helium from a commercial JfcOint of view resulted from the investigation of Cady and oIFarland,1 who found that the natural gas of Kansas nearly llvvays contained helium, in some samples the amount present felting from 1.5 to 1.84 per cent. It is from such sources that commercial helium is being developed. 

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