Oxygen : The Most Abundant Element
OXYGEN : The Most Abundant Element
Oxygen, so far is the most abundant element in the earth’s crust, accounting for about 50 % of its mass. Most rocks contain large percentage of oxygen, and sand ( Silicon dioxide SiO2) is more than 50 % Oxygen by mass. Oxygen accounts for about 21% of the volume of our atmosphere in the form of free Oxygen (O2), 66 .67% of the mass of the human body and about 90% of the mass of the earth’s ocean. About ¼ of the atoms in living organisms are Oxygen atoms. Molecules of Oxygen (O2) is also essential in metabolism.
The name Oxygen was given by Lavoisier, from the Greek words meaning “sour’ and ‘to produce’. Oxygen was first obtained by Stephen Hales in 1727, but he failed to recognize it as a new element . Priestly discovered it in 1774, while heating mercuric oxide with the aid of a “ burning glass.”
In combination with Carbon , Hydrogen, and Nitrogen, it enters into the structure of all human life, being an important constituent of sugar, starch, fats, albumen, all Carbohydrates and proeids, woody fiber, etc.
Oxygen gas is odorless, tasteless and colorless with melting point -218 degrees Celsius and boiling point -183 degrees Celsius. It exist as solid below -227 degrees Celsius,As a liquid between -227 degrees Celsius and -182 degrees Celsius and as gas above -182 degrees Celsius. Both liquid and solid Oxygen are light blue in color.
Oxygen is most often prepared commercially by distilling liquid air obtained fron the earth’s atmosphere, Over 400 billion cubic feet is produced in this way every year.The Oxygen in our atmosphere is continually replenished by the “photosynthesis” of plants – a process in which plants convert Carbon dioxide (CO2) and water (H2O) producing Oxygen (O2) and carbohydrates such as glucose in the presence of light and chlorophyll.
6 CO2 + 6 H2O =è C6H12O6 + 6 O2
It has been estimated that each year plants convert over 10 raise to the tenth power metric tons of Carbon into Carbohydrates , producing as a byproduct about 3 X 10^10 metric tons of Oxygen.
Small amounts of Oxygen can be produced in the laboratory by the thermal decomposition of Potassium Chlorate, to which a small amount of manganese oxide has been added.
2 KClO3 ==è 2 KCl + 3 O2
USES OF OXYGEN
Oxygen is the fifth most important industrial chemical in the United States , where over 35 billion pounds of it are sold annually. Its major commercial use about 65% is in blast furnaces in the manufacture of steel. Oxygen increases the rate of combustion and thereby produces a higher temperature.
Oxygen is also used in the hospitals; in the breathing apparatus of divers, high mountain climbers and astronauts. A very important use of Oxygen is in metabolism. An average resting human adult consumes about 500 Liters (at STP) of Oxygen per day. No ordinary combustion can take place without Oxygen.
Precision And Design
By Verne Biddle