Does water oxidized spontaneously on nature?

Submitted by LeeAnn1409 t3_z1sxtl in askscience

My chemistry teacher was talking about oxidation of water and explained that it happens spontaneously in nature that most of the oxygen in the world comes from water bodies rather than trees Is this true? If so, how much oxygen comes from water?

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SeagullsGonnaCome t1_ixdu781 wrote

Oxidation does happen spontaneously just as a chemical reaction. But it's not kinetically favorable...

It usually requires a catalyst.

And yes, the ocean does produce the majority of O2.

That is because the ocean is home to photosynthetic plankton. 😎

Plankton living in the ocean, oxidizing water to oxygen through photosynthesis, is responsible for the majority of oxygen in the atmosphere.

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Nussinsgesicht t1_ixdulhq wrote

That's definitely not true, theres good reason the presence of O2 is a valuable diagnostic both when looking at the ancient Earth and when looking at distant planets, appreciable quantities don't typically happen on their own. That's not to say that water is never oxidized spontaneously, but it's negligible compared to photosynthesizers

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-space_ghost- t1_ixe1zcm wrote

One Strange Rock has an episode devoted to how Earth produces and uses Oxygen. It's thoroughly explained, and easy to understand; probably a great place for you to start learning about this topic a little more in depth. Check it out!

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CrDe t1_ixfx00r wrote

Almost all of the O2 in the atmosphere came from the cyanobacteria as a waste product of photosynthesis over the eons. As it happen trees, land plants and plants in general are eucaryote cells and eucaryotes have mitochondria that consume oxygen to produce energy. Cyanobacteria that happen to live in water and as there name suggest are bacteria, procaryote, therefore dont' have mitochondria. So it is so much that trees don't produce anything it's just that they also consume what they produce so their total output is marginal compared to organismes that expel all O2 as waste product.

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