Talk:Liquid air

Is this supposed to be relevant to a discussion on liquid air? The article title says "expert required" and refers here to talk page. What, in particular, are the needs of this article? Norm Reitzel (talk) 14:18, 2 May 2010 (UTC)

Boiling / freezing points

The "exact" boiling and freezing points of liquid air, quoted as

Its freezing point is -216.7 °C and its boiling point is -194.35 °C.

have been modified to reflect the fact that liquid air is a mixture and does not have well defined boiling and freezing points. Norm Reitzel (talk) 14:34, 2 May 2010 (UTC)

Liquid air does not have a boiling point/freezing point. By the way, I am an expert in chemistry.--J73364 (talk) 22:38, 6 February 2014 (UTC)

@J73364: Then you know that air's boiling point is determined by the lowest boiling point of its constituents, which is nitrogen. Below that point, all of its constituents are liquid.

By the same logic, its freezing point should also be the lowest of any of its constituents; this happens to be oxygen. The figure quoted here (-215 C) does not match the figure given in liquid oxygen, which is -222.6 C. Of course, that same logic might not hold up; below nitrogen's freezing temperature (-210 C) you should get nitrogen crystals floating in liquid oxygen, except that there's much more nitrogen than oxygen. This might affect the crystal formation of the whole. (I'm an engineer, but not a chemist.) JustinTime55 (talk) 18:55, 20 March 2015 (UTC)

Liquid air most certainly does have a well defined boiling point, just like any other solution with a definite composition. For a nearly ideal solution, the boiling point is always intermediate between the boiling points of its components. Look in any physical chemistry text in the chapter on solutions. You will find "boiling point diagrams" (sometimes called "temperature-composition diagrams") in the discussions of distillation and azeotropes. Those diagrams give the boiling point as a function of composition. I restored the boiling point listed above, although I am not certain it is the correct value and a reference is needed (couldn't find one in the time I have for this). Retired Pchem Prof (talk) 02:51, 14 January 2016 (UTC)

Liquid air versus liquid nitrogen for cooling

Liquid nitrogen is a widely used commodity and has largely replaced liquid air for cooling because it is safer. Liquid air tends become enriched in liquid oxygen as it evaporates, which can cause explosions in contact with materials like carbon. When oxidizing, rather than cooling, properties are desired liquid oxygen is used instead. Therefore I doubt that liquid air would be used in theatrical fog making.CharlesHBennett (talk) 15:05, 22 June 2014 (UTC)

I have just located online information about the use of liquid air for theatrical fog effects. It seems it is accurate.

Regards, Lindsay 149.254.58.79 (talk) 18:15, 16 March 2015 (UTC)

It might be worth noting the safety risks and benefits of liquid air in the article. The risks (primarily oxygen enrichment) have been stated above but one benefit, especially in the theatre context, is that it does not lower the concentration of oxygen in a room as it evaporates and therefore mitigates the suffocation risk associated with LN266.38.56.124 (talk) 14:50, 5 October 2015 (UTC)

References

Could use some restructuring

The applications section should really mention Grid energy storage (even if the relevant article has yet to highlight liquid air properly), as well as Air separation. So yeah reworking, separation into subsections VoidLurker (talk) 12:57, 7 June 2013 (UTC)

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Preparation / Process of Manufacturing

Under this subsection, the categorization of high pressure and low pressure set at >75 atm and <25 atm respectively. The closest reference leads to a Linde page that doesn’t really define these values.

Working in cryogenics at air separation plants I believe it is the case of wrong units. The plants that I’ve worked at (in the us) operate their double columns at essentially ~75 psia ish and ~25 psia ish. Which are nowhere near 75 and 25 atm clearly.

I am not sure how best to reference or prove this , hence why created a discussion point and not a suggestion. 2600:1005:B102:CA7A:54B1:282B:8278:792 (talk) 19:40, 14 December 2022 (UTC)