Has all the oxygen been breathed?

Question

Apparently most the water on the world has been cycled around the planet, streams to rivers, rivers to sea, sea to clouds, clouds to rain, rain to river, is it the same with all the oxygen has it all been breathed at sometime by a living organism? Its Friday and I'm bored

Answer 1

If you're bored, maybe you can work it out.
All the tonnes of water contain ______ tons of O in H2O.
All the tonnes of silicon dioxide (sand, quartz, etc.) contain ______ tonnes of O in the SiO2
All the tons of limestone in coral reefs above and below the sea contain _______ tons of O in the form of CaCO2.
All the tonnes of air contain 20% O which is _______tonnes
If each person has a lung capacity of 0.5L per breath and breathes about 15 times a minute. The world population was 6.6B this summer. If we make the extreme estimate that this is the same number as all the humans lived before, then 13.2B and if we make extreme assumption that average life was 50 years or about 26M minutes each then all of the population in all of their lives would take in 13.2B x 26M x 15 x .5L x 20% = 6.11e178 liters of O.
The dry air mass is 5.1352 ±0.0003×10^18 kg at about 1.2 kg/m^3 is about 4.4x10^18 m^3 or 4.4x10^21 L.
The O breathed by the people is such a huge number (6 followed by 178 zeros) that is so much larger than air in atmosphere (ratio about 1.5 followed 157 zeros) that it certainly has all been breathed. It is only after figuring all the O in the water and solids that one could be sure.
That is left to student.

Answer 2

You should indeed do some calculations to get a better feel for the answer. It is believed that the earth had no elemental or O2 oxygen for most of its early history. Certain marine algae are though responsible for earth's initial oxygen.

Once you decide what you mean by the question, consider a molecule of O2 released into the atmosphere today by a tree in the Amazon jungle, or by a phytoplankton in the Arctic ocean. What are the chances it will never find its way to animal to support its respiration?

Answer 3

Think there's some terrible ignorant answers.

When be breathe out we breathe out Carbon Dioxde, one carbon, two oxygen. Plants need the carbon so take in the Carbon dioxde, keep the carbon, and give out oxygen- the same oxygen that was breathed in by the original person.

So the question is- have all the oxgen molecules in the world at some point been breathed in or respired by a living creature. I think probably.

Answer 4

Yes it must have or we would have run out years ago.... The majority of the oxygen in our atmosphere (as someone else stated) is a 'plant' by-product (splitting water [H2O]), while fixing atmospheric carbon into carbohydrate (CHO). At a later stage CHO is either oxidised with atmospheric O2 by the plant itself or by animals that have consumed the CHO. This process (respiration) releases both CO2 and H2O. Thus the 2 inter-linked processes, cycle both oxygen and carbon; being driven by solar energy during photosynthesis which empowers hydrogen to do the job!!

Answer 5

The air is about 21% oxygen and 19% nitrogen. It is continually replaced by plants in photosynthesis. There is even oxygen in the breath we breathe out. If not artificial respiration would not work.

Answer 6

In nature, FREE oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis in cyanobacteria, green algae and plants.[27] Algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on earth.[28] The remainder is produced by terrestrial plants, although almost all oxygen produced in tropical forests is consumed by organisms in those forests.[29]

So yes - all breathable o2 has been "respired" by something living before you ever get to breath it...

Answer 7

Yes just like all water has been through the water cycle the world is just a cycle.We breathe it out into carbon dioxide and plants turn it back into oxygen which recycles it which is why we should stop killing trees! :)

Answer 8

Remember plants give off oxygen, so more is being produced all the time by all the plants/trees on the planet.

Answer 9

Not in the mood to do the calculation but I would think you are correct, apart from the very small percentage that enters the atmosphere system from volcanic emissions and similar long-term sequestration sites.

Answer 10

Yes all the air you breath has been breathed by next doors dog.
Next time you fill you kettle, just think, the water has been flushed down my toilet.