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Liquid oxygen has a clear cyan color and is strongly paramagnetic: it can be suspended between the poles of a powerful horseshoe magnet. [2] Liquid oxygen has a density of 1.141 kg/L (1.141 g/ml), slightly denser than liquid water, and is cryogenic with a freezing point of 54.36 K (−218.79 °C; −361.82 °F) and a boiling point of 90.19 K (−182.96 °C; −297.33 °F) at 1 bar (14.5 psi).
One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas comes into a supercritical phase, and so cannot be liquefied by pressure alone.
At high enough altitudes the partial pressure of oxygen in the air is insufficient to support useful work and consciousness, even after acclimatisation, and at even higher altitudes it cannot support human life. At altitudes where the problem is hypoxia, breathing gas with a higher oxygen content at ambient pressure is a viable solution.
Freezing is a phase transition in which a liquid turns into a solid when its temperature is lowered below its freezing point. [ 1 ] [ 2 ] For most substances, the melting and freezing points are the same temperature; however, certain substances possess differing solid-liquid transition temperatures.
Most humans can function at rest with an oxygen level of 15% at one atmosphere pressure; [1] a fuel such as methane is combustable down to 12% oxygen in nitrogen. A small room of 10 meter 3 has 2.08 meter 3 (2080 liters) or 2.99 kg of oxygen which would occupy 2.62 liters if it was liquid. [2]
He had produced oxygen gas by heating mercuric oxide (HgO) and various nitrates in 1771–72. [18] [19] [10] Scheele called the gas "fire air" because it was then the only known agent to support combustion. He wrote an account of this discovery in a manuscript titled Treatise on Air and Fire, which he sent to his publisher in 1775. That ...
Dry air: 159: Air is ~21% oxygen [2] Moist air: 150: Air is humidified in the respiratory tract [2] Alveolar air: 110-100: Alveolar air includes exhaust gases such as CO 2 [2] [3] Arterial blood (PaO 2) 98-95: Oxygen must cross the alveoli, leading to a drop in PO 2 called the alveolar-to-arterial gradient (typically a drop of 1-5 mmHg, but ...
Gas exchange occurs in the lungs, whereby CO 2 is released from the blood, and oxygen is absorbed. The pulmonary vein returns the now oxygen-rich blood to the left atrium. [10] A separate circuit from the systemic circulation, the bronchial circulation supplies blood to the tissue of the larger airways of the lung.