Why can’t we just harvest the oxygen in H20 and breathe under water
In: Chemistry
I’m going to first assume you mean splitting the water molecule:
Chemicals react one of two ways: by using up energy (endothermic), or releasing stored energy (exothermic).
Creating water from hydrogen and oxygen is an exothermic reaction – fusing oxygen and hydrogen **creates water** but also releases energy, in the form of heat.
In general, reversing an exothermic reaction is endothermic: you need to add heat BACK INTO the system for the reaction to go the other way.
What that means is to **split water** up into hydrogen and oxygen, you need energy, and a lot of it. It’s an amount of energy that would be impossible to reliably supply underwater, and would be nowhere near as efficient as filling a tank full of oxygen.
If you don’t mean splitting the water molecule, but you do mean extracting the dissolved oxygen in water (this is how fish breathe, they do not split molecules of h2o) the same answer as above pretty much still applies: the chemistry to do it efficiently would never outpace the reliability and efficiency of filling a tank with oxygen.
We need more oxygen than fish and water doesn’t have that much dissolved oxygen in it. You would need to reliably extract the dissolved oxygen from tens of liters of water PER MINUTE to stay alive down there. Or you can get a massive metal tank and fill it with oxygen that can be made comfortably on land.
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