Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: eternity on 20/03/2014 03:45:27

Title: How is oxygen made?
Post by: eternity on 20/03/2014 03:45:27

Its been a while since I went to school so I was wondering if anyone could help me?

I know that oxygen can be made in stars (is it nuclear fission?) by carbon and helium fusing.

I also know that plants can make oxygen from carbon dioxide and water.

How is this possible? One needs a great amount of heat and the other doesn't.

Please help me understand the similarities or differences, I'm utterly confused.

Thank you
Title: Re: how is oxygen made?
Post by: chiralSPO on 20/03/2014 03:58:02
The problem is ambiguity in the word oxygen.

Oxygen the element is a single atom, containing 8 protons in the nucleus (and usually, but not necessarily 8 neutrons too). It is a product of nuclear fusion (combining lighter nuclei) in stars, and can also be formed by fission (breaking) of heavier nuclei.

Oxygen the molecule is two oxygen atoms bound together (2 oxygen nuclei and 16 electrons). It can be created by combining oxygen atoms (already formed in a star long ago). Plants produce molecular oxygen from water--this does require energy (provided by fusion in our own sun!), but not nearly as much as is needed for fusion.
Title: Re: how is oxygen made?
Post by: eternity on 20/03/2014 05:40:14
ah, ok. So one is an element and the other a molecule.

That clears it up!

Thank you very much!
Title: Re: how is oxygen made?
Post by: CliffordK on 20/03/2014 11:32:44
NEW Oxygen is made in stars by nuclear fusion, and perhaps some radioactive decay.

Plants simply recombine the chemical bonds in Carbon Dioxide (CO2) and Water (H2O), along with some other nutrients to form various hydrocarbons, sugars, starches, proteins, and etc.  The oxygen is released as a waste product. 

In the interior of stars, most of the atoms exist as a plasma, without particularly having a molecular structure. 

On Earth, oxygen as a monomer (O) can exist, at least for a short period and is considered to be a free radical which is highly reactive.  More commonly it forms a dimer (O2), or a trimer (O3/Ozone).  It also combines to form molecules with many other elements or combinations of elements.