Oxygen, abbreviated O2, is a colorless, odorless, non-flammable gas.   It is an oxidizing gas at high pressure. Oxygen constitutes approximately 21% of the air.  When considered in other combinations such as water (H2O) oxygen makes up about 49% of the molecules on the earth's crust.The oxygen molecule has a gaseous specific gravity of 1.1, and a boiling point . Oxygen is produced by air separation processes that use either cryogenic liquefaction and distillation or vacuum swing adsorption (VSA) separation.  Oxygen can be stored and shipped as either a gas or a cryogenic liquid. The principal uses of oxygen stem from its strong oxidizing and life-sustaining properties.  It is used in medicine for therapeutic purposes.  Oxygen is used in the metals industry in conjunction with acetylene and other fuel gases in metal cutting, heating, welding, hardening, scarfing, cleaning, and dehydrating.  In the chemical and petroleum industries, oxygen is used in the production of synthetic gas from coal, natural gas, and liquid fuels. 
In order to grasp the concept of molar mass calculations it is important to understand the molar unit. The mole also called mol is the basic unit of measurement in chemistry. By definition, in modern chemistry, one mole represents the number of carbon atoms in exactly 12 grams of carbon 12 isotope. Remember that carbon-12 has an atomic mass of 12 (six neutrons and six protons). One mole of anything, however, contains 6.0221367E23 of that object. This is known as Avogadro's number. Examples:1 mole of carbon = 6.0221367E23 carbon atoms;1 mole of bananas = 6.0221367E23 bananas
Obviously it would be impossible to count out 6.0221367E23 atoms. Remember, however that 1 mole of carbon-12 = 12 grams = 6.0221367E23 atoms. It has been established that 1 mole of any element = the atomic mass of that element expressed in grams. Since magnesium has an atomic mass of 24, one mole of magnesium weighs 24 grams and contains 6.0221367E23 atoms of magnesium. A mole of any molecule = the molecular mass of that molecule expressed in grams. In order to determine the weight of one mole of bananas, one would have to get an average weight of a banana and multiply that by 6.0221367E23 then we could weigh out that weight of bananas and presto, we would have a mole of bananas. Of course, nobody would ever do that. It just demonstrates that mole of anything = 6.0221367E23 and we can measure out a mole of something by counting it or by weighing it out. Since atoms are too small to count, we must weigh out a mole of atoms. Molar massis a unit that enables scientists to calculate the weight of any chemical substance, be it an element or a compound. Molar mass is the sum of all of the atomic masses in a formula. Once one determines the molar mass of a substance, it will be easy to measure out one mole of that substance. 




