Fractional distillation of liquid air

Industrially, elemental nitrogen is extracted from the air by the fractional distillation of liquid air from which carbon dioxide and water have been removed. The major fractions are nitrogen, b.p. 77 K and oxygen, b.p. 90 K, together with smaller quantities of the noble gases. 

Ammonia is synthesised from its elements nitrogen and hydrogen. The nitrogen is obtained by the fractional distillation of liquid air. The hydrogen is obtained by the reaction of methane (from natural gas) with steam. 

Preparation. The only important large-scale process is the fractional distillation of liquid air. 

Krypton is the 81st most abundant element on Earth and ranks seventh in abundance of the gases that make up Earths atmosphere. It ranks just above methane (CH ) in abundance in the atmosphere. Krypton is expensive to produce and thus has hmited use. The gas is captured commercially by fractional distillation of liquid air. Krypton shows up as an impurity in the residue. Along with some other gases, it is removed by filtering through activated charcoal and titanium. 

Xenon is found in trace amounts in the atmosphere. It makes up just 0.086 ppm by volume of air. Xenon is the rarest of the noble gases. For every thousand-million atoms of air, there are only 87 atoms of xenon. Even so, it is recovered in commercial amounts by boiling off the xenon from fractional distillation of liquid air. Small amounts of xenon have been found in some minerals and meteorites, but not in amounts great enough to exploit. 

Oxygen occurs as the free element (O2) in the atmosphere (21%), from which it is obtained by fractional distillation of liquid air or by membrane technologies, but far greater amounts are found in the Earth s crust in... 

The nitrogen required is obtained by fractional distillation of liquid air.16 The hydrogen used to be obtained by electrolysis of liquid water if inexpensive surplus electrical capacity becomes available in the future, this method may well be reintroduced. Catalytic photolysis of water using sunlight is another possible future source of H2. The Haber-Bosch process of 1916 used water-gas, which is a mixture of H2, CO, and CO2 made by alternating blasts of steam and air over coke at red heat ... 

More than 2 X 1010 kg of liquid oxygen are produced each year in the United States (about 80 kg per inhabitant) by fractional distillation of liquid air. The biggest consumer of oxygen is the steel industry, which... 

Helium is separated from natural gas by the liquefaction of the other gases. The other noble gases are obtained in large quantities by the fractional distillation of liquid air (Chapter 11, p. 174). 

Air is the major source of oxygen, nitrogen and the noble gases. The gases are obtained by fractional distillation of liquid air but it is a complex process, involving several different steps (Figure 11.8). 

Nitrogen may also be produced directly from air by the fractional distillation of liquid air or by passing air over heated copper. In the latter case, oxygen is removed by combination with the copper to form copper oxide, but the resulting nitrogen is not entirely pure since it is contaminated by the inert gases present in the original sample of air. 

Nitrogen is made commercially by the fractional distillation of liquid air. In the laboratory it is conveniently made, in slightly impure form, by removing oxygen from air. It may also be made by the oxidation of ammonia by hot copper oxide ... 

The nitrogen for this process is obtained from fractional distillation of liquid air. Although originally obtained from electrolyis of water, H2 is now obtained more economically from hydrocarbons (see p. 248). 

Nitrogen is produced commercially almost exclusively from air, most commonly by the fractional distillation of liquid air. In this process, air is first cooled to a temperature below that of the boiling points of its major components, a temperature somewhat less than -328°F (-200°C). The liquid air is then allowed to warm up, allowing the lower-boiling-point nitrogen to evaporate from the mixture first. Nitrogen gas escaping from the liquid air is then captured, cooled, and then liquefied once more. 

The lithosphere contains about 47% oxygen by weight, and the oceans about 89%. The atmosphere has 20.95% oxygen by volume the element is obtained by the fractional distillation of liquid air. Oxygen is decidedly... 

Rayleigh and Ramsay discovered argon by the fractional distillation of liquid air. Fractional distillation is the process of letting liquid air slowly warm up. As the air warms, different elements change from a liquid back to a gas. The portion of air that changes back to a gas at -302.55°F (-185.86°C) is argon. 

Derivation (1) By fractional distillation of liquid air. (2) By the treatment of atmospheric nitrogen with metals such as magnesium and calcium to form nitrides. (3) Recovery from natural gas oxidation bottoms-steam in ammonia plant. (4) Originally formed by radioactive decay of K. 

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