Water vapor turns into oxygen and hydrogen
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At what temperature or under what other conditions does water vapor turn into O2 and H2? Thank you, extra points, even more points.
I remember it was mentioned in 【One Hundred Thousand Whys】
Water vapor condensed into water and then electrolyzed can be turned into oxygen and hydrogen.
The lower limit for the decomposition and conversion of water vapor depends on two factors: 1. Conversion to a supercritical fluid: Water transforms into a supercritical fluid when both the critical pressure and critical temperature are exceeded; these values are 374°C at 218 atmospheres. However, at one atmosphere of pressure, water vapor can remain gaseous at thousands of degrees. 2. Thermal decomposition of water: It is said to require temperatures above 5000°C, and this involves a series of thermodynamic calculations. The hydrogen-oxygen flame produced during the combustion of hydrogen and oxygen can reach temperatures of 2500–3000°C. Water is still formed during combustion at these temperatures, which indicates that water hardly decomposes at such high temperatures.
Currently, the mature technology is electrolytic water generation. In laboratory experiments, there are membrane separation techniques as well as optical separation techniques; simple methods such as heating alone seem to not work.