Oxygen third most profusely found element in the universe Commercially, oxygen can be prepared by the process of liquefaction and fractional distillation of air and through electrolysis of water

1. Orgin, History and
Evolution of Oxygen
Article written and posted
By
www.worldofchemicals.com

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Oxygen is the third most profusely found element in
the universe. It is naturally found in the sun and
plays a significant role in the carbon cycle. Being the
primary member of Group 16 of the periodic table,
oxygen is a chemically active element, forming
compounds with nearly all the elements except the
inert gases. It is paramagnetic in all its three forms;
i.e., solid, liquid, and gaseous state.
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Oxygen is denser than air and can be dissolved in
water up to an explicit extent. Commercially, oxygen
can be prepared by the process of liquefaction and
fractional distillation of air and through electrolysis of
water
Introduction

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Oxygen combines directly with various elements to form oxides. Oxygen is
present as important constituent of many acids, hydroxides, and various other
compounds. A vital feature of oxygen includes when cooled below its boiling
point, oxygen turns into a pale blue liquid and when cooled even more, the
liquid solidifies while retaining its color.
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Oxygen is a poor conductor of heat and electricity. The natural oxygen in the
atmosphere called diatomic oxygen gas has a molecular mass of 32
while ozone (O3), which is more reactive than natural oxygen, is another
allotrope of oxygen formed due to electrical discharges or ultraviolet light
reacting with the atmospheric oxygen. In its molecular form, oxygen is found
almost anywhere in the atmosphere.
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Oxygen is regarded as highly reducing gas. It tends to combine with other
molecules like atmospheric gases or surface rocks. It is the second-most
electronegative atom in the periodic table after fluorine. Oxygen has a strong
tendency to rip electrons from other atoms. As a consequence, any given
oxygen molecule has a relatively short lifetime in the atmosphere.
Introduction Cont ..

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Prior to 3.45 billion years ago, Earth's atmosphere
and oceans were anoxic (i.e. without oxygen). This is
supported by the existence of mass-independent
fractionalization (MIF) of sulfur isotopes in sediments
from this time period, for these can only form in the
absence of oxygen.
Then, during the periods between 2.45 and 1.85
billion years ago, molecular oxygen appeared.
Photosynthesis is the main process for plant through
which some amounts of oxygen get released into the
environment. Other than plants few kinds of bacteria
called cyanobacteria also able release oxygen.
History of oxygen evolution

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Oxygen levels have since continued to more-or-less rise,
peaking at 30 per cent of the total atmospheric content
during the Carboniferous era some 350 million years ago.
During this time, the burial rate of organic matter was
rapid, preventing oxygen from combining with carbon in
dead organisms and keeping it in the atmosphere.
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The high availability of oxygen during this period may
explain the enormous insects of the Carboniferous era.
Oxygen also plays vital role in animals. If more oxygen is
available to the absorbed into the animal blood, then blood
may deliver the oxygen further into different parts of body,
thereby oxygen supporting larger body structures in
animals.
History of oxygen evolution Cont ..

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Several models assume that during the Proterozoic Eon
(Proterozoic Eon era ranges from 2.5 billion to 542 million years
ago), the concentration of oxygen in the ocean was substantially
lower than atmospheric oxygen levels.
Oxygen evolution is the process of generating molecular oxygen
through chemical reaction. Mechanisms of oxygen evolution
include the oxidation of water during oxygenic photosynthesis,
electrolysis of water into oxygen and hydrogen, and
electrocatalytic oxygen evolution from oxides and oxoacids.
Photosynthetic oxygen evolution occurs via the light-dependent
oxidation of water to molecular oxygen and can be written as the
following simplified chemical reaction
2H2O → 4e- + 4H+ + O2
History of oxygen evolution Cont ..

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The reaction requires the energy of four photons. The
electrons from the oxidized water molecules replace
electrons in the P680 component of photosystem II that
have been removed into an electron transport chain via
light-dependent excitation and resonance energy transfer
onto plastoquinone. Photosytem II, therefore, has also
been referred to as water-plastoquinone oxido-reductase.
The protons are released into the thylakoid lumen, thus
contributing to the generation of a proton gradient across
the thylakoid membrane. This proton gradient is the
driving force for ATP synthesis via photophosphorylation
and coupling the absorption of light energy and oxidation
of water to the creation of chemical energy during
photosynthesis.
History of oxygen evolution Cont ..

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Oxygen evolution occurs as a byproduct of hydrogen production
via electrolysis of water. While oxygen production is not the main
focus of industrial applications of water electrolysis, it becomes
essential for life support systems in situations that require the
generation of oxygen for air revitalization.
Human exploration of regions that lack breathable oxygen, such
as the deep sea or outer space, requires means of reliably
generating oxygen apart from earth's atmosphere. Submarines
and spacecraft utilize either an electrolytic mechanism (water or
solid oxide electrolysis) or chemical oxygen generators as part of
their life support equipment.
Rising oxygen concentrations have been cited as a driver for
evolutionary diversification, although the physiological arguments
behind such arguments are questionable, and a consistent
pattern between oxygen levels and the rate of evolution is not
clearly evident.
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History of oxygen evolution Cont ..

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Oxygen reacted with iron in seawater, and the resulting iron oxide precipitated
onto the seafloor, and then was buried deep within the Earth.
Oxygen-rich water in seafloor sediments was buried within the Earth, leaving
oxygen in the mantle when the water's hydrogen was belched out by
volcanoes.
Oxygen-rich sulfates in undersea hot springs reacted with iron in seafloor
sediments, which were buried to put oxygen into the mantle.
According to carbon-burial theory when organic material is buried, oxygen
becomes available to build up in the atmosphere. So there was a sudden
increase 2.3 billion years ago in the amount of organic carbon that was buried,
leaving more free oxygen.
Oxygen prevents growth of the most primitive living bacteria such as
photosynthetic bacteria, methane-producing bacteria and bacteria that derive
energy from fermentation.
There are three hypothetical theories
for oxygen evolution

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[1] © From,
http://www.ch.ic.ac.uk/rzepa/mim/environmental/ht
ml/oxygen_text.htm
[2] © From, http://www.usesof.net/uses-ofoxygen.html
[3] © From,
http://www.ucc.ie/academic/chem/dolchem/html/ele
m008.html
[4] © From,
http://www.astrobio.net/exclusive/541/the-rise-ofoxygen
[5] © From,
http://newworlds.colorado.edu/search/o2.htm
http://www.worldofchemicals.com/wocart/437/theorigin-and-geological-history-of-oxygen.html
References