How much oxygen is there on Earth ? The total mass of the Earth’s atmosphere, including the oxygen, is estimated to be about 5.15 x 1018 kilograms, or approximately 5.67 x 1015 tons. The concentration of oxygen in the atmosphere is about 20.95% by volume, which means there is around 20.95% of oxygen in the atmosphere. Therefore, the mass of oxygen in the atmosphere would be approximately 20.95% of 5.67 x 1015 tons, which is about 1.19 x 1015 tons.
That’s our best quick answer, but we have seen other figures.
One site put the atmosphere containing about 1.3 x 1014 tons of free oxygen today, also saying that in 1492, the atmosphere was much larger ( 2.0 x 1014 tons) and wider in diameter due to the presence of nearly 9 Billion more acres of Tree growth. The same site stated that the lithosphere, the Earth’s crust, carries an even larger amount of bound oxygen, 5.5 x 1016 tons, more than a hundred times that found in the atmosphere. The site says that the lithosphere in 1492 “bore nearly 6.75 x 1016 tons, so there has been some lithospheric reduction as well.”
Here’s what Britannica says:
The total mass of Earth’s atmosphere is about 5.5 quadrillion tons, or roughly one millionth of Earth’s mass. Earth’s atmosphere extends from its ocean, land, and ice-covered surface outward into space, and its density is greatest close to the surface, because the gravitational attraction of the planet pulls the gases and aerosols (microscopic suspended particles of dust, soot, smoke, or chemicals) inward. Air is heavier (and thus easier to breathe) at sea level, since the air molecules sit close together, compressed by the weight of air from above. As elevation increases, however, air molecules spread farther apart, and the air becomes lighter.
How much is 5.5 quadrillion tons in scientific notation? It is written as 5.5 × 1015 tons.
As far as an official source, here is what one NASA web site with Earth facts shows the atmosphere mass as 5.1 x 1018 kg, which is 5.1 quadrillion tons, close to the higher figure thaa Britannica shows.
Total mass of atmosphere: 5.1 x 1018 kg
Note that to convert kilograms (kg) to tons, you need to divide by 1000 since there are 1000 kg in a ton.
Therefore, 5.1 x 1018 kg is equal to (5.1 x 1018) / 1000 = 5.1 x 1015 tons.
Atmospheric composition (by volume, dry air):
Major : 78.08% Nitrogen (N2), 20.95% Oxygen (O2),
Minor (ppm): Argon (Ar) - 9340; Carbon Dioxide (CO2) - 415
Neon (Ne) - 18.18; Helium (He) - 5.24; CH4 - 1.7
Krypton (Kr) - 1.14; Hydrogen (H2) - 0.55
The difference between the Britannica figure in tons and the NASA figures in kilograms is because there are 1,000 quadrillions in 1 quintillion.
Some Notes
Does the difference in the molar mass of N2 and O2 change your ability to determine the amount of O2 in a total mass of atmosphere of you know the percentage? Some clues for this answer:
Molar Mass:
Molar mass, also known as molecular weight, is the mass of one mole of a substance. It is measured in units of grams per mole (g/mol). Molar mass is often calculated by adding up the atomic masses of all the atoms present in a molecule, using the periodic table as a reference. It is used extensively in chemistry for various calculations, including determining the amount of substance in a given mass or vice versa, as well as in stoichiometry and other related concepts.
A Mole:
In chemistry, a mole is a unit that represents a specific amount of a substance. The mole is defined as the amount of a substance that contains as many particles (atoms, molecules, ions, etc.) as there are atoms in exactly 12 grams of carbon-12. This number of particles is called Avogadro’s number, approximately 6.022 x 1023. The mole is used to measure and express the quantities of chemical substances. It allows chemists to easily convert between mass, number of particles, and volume of substances in various chemical reactions and calculations. For example, the molar mass of a substance is the mass of one mole of that substance, expressed in grams.
Gas Percentages:
Air is a mixture of several gases, where the two most dominant components in dry air are 21 vol% oxygen and 78 vol% nitrogen . Oxygen has a molar mass of 15.9994 g/mol and nitrogen has a molar mass of 14.0067 g/mol. Said another way, the for the same number of particles Oxygen has a higher mass than Nitrogen. If that number is a mole, or 6.022 x 1023, then that difference is that there are 1.9927 grams more mass for Oxygen. Since both of these elements are diatomic in air – O 2 and N 2 , the molar mass of oxygen gas is aprox. 32 g/mol and the molar mass of nitrogen gas is aprox. 28 g/mol. {EngrToolB}
How is Carbon, a solid, a lighter molecule than Nitrogen, and Oxygen even heavier than Nitrogen?
Carbon is a lighter molecule than nitrogen because it has a lower atomic mass. Carbon has an atomic mass of approximately 12 atomic mass units (amu), while nitrogen has an atomic mass of around 14 amu. The atomic mass is determined by summing up the protons and neutrons in the nucleus of an atom. Similarly, oxygen is even heavier than nitrogen because it has a higher atomic mass. Oxygen has an atomic mass of approximately 16 amu. The additional protons and neutrons in the oxygen atom contribute to its increased atomic mass compared to nitrogen. It is important to note that the atomic mass of an element is not solely determined by the number of protons (which defines the element), but also by the presence of neutrons in the nucleus. Different isotopes of an element can have different atomic masses due to varying numbers of neutrons.
