In the name of Allah the merciful

The chemical properties of Oxygen

By: Yaqeen Yesser

Oxygen, the most abundant element on Earth.

present on the Earth as gases (O2, O3, O4), H2O, and in countless chemical formulas

Oxygen composes 21 percent by volume or 23.15 percent by weight of the atmosphere, 85.8 percent by weight of the oceans (88.8 percent of pure water is oxygen), and as a constituent of most rocks and minerals, 46.7 percent by weight of the solid crust of the earth .

Oxygen comprises 60 percent of the human body .

It is a constituent of all living tissues, almost all plants and animals, including all humans, require oxygen, in the free or

combined state, to maintain life .

Three structural forms of oxygen are known: ordinary oxygen, containing two atoms per molecule, formula O2, ozone, containing three atoms per molecule, formula O3, and a pale blue, nonmagnetic form, O4, containing four atoms per molecule, which readily breaks down into ordinary oxygen.

Three stable isotopes of oxygen are known, oxygen 16 (atomic mass 16) is the most abundant. It comprises 99.76 percent of ordinary oxygen and was used in determination of atomic weights until the 1960s, Oxygen 17(atomic mass 17) and Oxygen 18 (Atomic mass 18) .

Oxygen supports lifeIts normal concentration in the air we breathe is

approximately 21%

We can breathe in a 50-60% oxygen enriched atmosphere for several hours under medical care (oxygen therapy)

Chemical Properties of O2 are:1-supports combustion.

As the oxygen concentration in air increases, the potential fire risk increases .

At concentrations above 23 % in air, the situation becomes dangerous due to the increased fire hazard.

Because oxygen is colourless, odourless and tasteless.

by oxygen enrichment can’t be detected by the normal human senses

As we see here The oxygen doesn’t burn but supports the

combustion……

Necessary conditions for a fire

For a fire or explosion to occur, three elements are required:

Combustible material,Oxygen

Ignition source

As we know Oxygen doesn’t burn but support burning .……

No flame in oxygen enriched atmospheresOxygen enriched atmosphere can occur at:Pits, trenches,Low enclosed areas, underground waysSewers

In ASU, cylinder filling plants…,Around tanker fillingAround vents, leaks…

In such areas: o Don’t smokeo Don’t Use Naked flameso Don’t weld o Wear adequate fire-resistant or cotton garments and under clothing.

2-React with Non-metals: Example (Put quantity of Sulphur powder in Spoon Ignition then heat it on flame , we notice Sulphur combustion , and enter the spoon in a bottleful that includes oxygen gas, Then we see increasing the combustion of Sulphur inside the bottleful , and appearance of foggy

material.....

The conclusion of that behavior is: the increasing of Sulphur combustion in The Oxygen gas bottleful and forming the foggy material is an evidence for Sulphur reaction with Oxygen then forming Sulphur dioxide gas (SO2)…As below in the equation:

S + O2 SO2

3-React with metals: the Oxygen reacts with most of metallic elements that yield metallic oxides..ex: when combustion of Magnesium ribbon in Oxygen gas, then it will form a white powder is Magnesium oxide (MgO) , as below:2Mg + O2 2MgO..……………

Another example is shown in photo:

2Mg (s) + O2 (g) 2MgO(s)

4Fe (s) + 3O2 (g) 2Fe2O3(s)

4Li (s) + O2(g) 2Li2O (s)

2Cr(s) + 3O2(g) 2CrO3(s)

4Cu(s) + O2(g) 2Cu2O(s)

The operation of reaction of oxygen and elements is called

(Oxidation..…………)

Thank U so much for listening

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