Atomic Mass Of Oxygen



Atomic Mass Of Oxygen

Dry air is a mixture of gases where the average molecular weight (or molar mass) can be calculated by adding the weight of each component

The molecular weight (or molar mass) of a substance is the mass of one mole of the substance, and can be calculated by summarizing the molar masses of all the atoms in the molecule.

Components in Dry Air

Oxygen

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. Since both of these elements are diatomic in air - O2 and N2, the molar mass of oxygen gas is aprox. 32 g/mol and the molar mass of nitrogen gas is aprox. 28 g/mol.

O I Ground State 1s 2 2s 2 2p 4 3 P 2 Ionization energy 109837.02 cm-1 (13.61805 eV) Ref. MG93 O II Ground State 1s 2 2s 2 2p 3 4 S° 3 / 2 Ionization energy 283270.9 cm-1 (35.1211 eV) Ref. MKM93-1 (35.1211 eV) Ref. Name: Oxygen Symbol: O Atomic Number: 8 Atomic Mass: 15.9994 amu Melting Point:-218.4 °C (54.750008 K, -361.12 °F) Boiling Point:-183.0 °C (90.15 K, -297.4 °F) Number of Protons/Electrons: 8 Number of Neutrons: 8 Classification: Non-metal Crystal Structure: Cubic Density @ 293 K: 1.429 g/cm 3 Color: colorless Atomic Structure. The amu (physical scale) was one-sixteenth of the mass of an atom of oxygen-16. The amu (chemical scale) was one-sixteenth of the average mass of oxygen atoms as found in nature. 1 u = 1.000 317 9 amu (physical scale) = 1.000 043 amu (chemical scale) 1. The mole and the unified atomic mass unit. Metrologia, volume 33, pages 261. Atomic Number of Oxygen. Oxygen is a chemical element with atomic number 8.

The average molar mass is equal to the sum of the mole fractions of each gas multiplied by the molar mass of that particular gas:

Atom

Mmixture = (x1*M1 + ......+ xn*Mn) (1)

where

Atomic Mass Of Oxygen 17

xi = mole fractions of each gas
Mi = the molar mass of each gas

The molar mass of dry air with oxygen, nitrogen and the other components as indicated below is 28.9647g/mol. Composition and content of each gas in air is given in the figures and the table below.

See also AirDensity at varying pressure,Density and specific weight at varying temperature, Diffusion Coefficients for Gases in Air, Dynamic (absolute) and kinematic viscosity, Prandtl Number, Specific heat at varying temperature and Specific heat at varying pressure, Thermal Conductivity, Thermal Diffusivity, Properties at gas-liquid equilibrium conditions and Air properties, for other properties of air.


Oxygen

For full table with Molar mass an Molar mass in Air - rotate the screen!

Components in dry airVolume ratio = Molar ratio,
compared to dry air
Molar Mass
Molar mass in air
NameFormula[mol/molair][vol %][g/mol]
[kg/kmol]
[g/molair]
[kg/kmolair]
[wt %]
NitrogenN20.7808478.08428.01321.87398375.52
OxygenO20.2094620.94631.9996.70246923.14
ArgonAr0.009340.93439.9480.3731141.29
Carbon dioxideCO20.000330.03344.0100.0146770.051
NeonNe0.000018180.00181820.1800.0003670.0013
HeliumHe0.000005240.0005244.0030.0000210.00007
MethaneCH40.000001790.00017916.0420.0000290.00010
KryptonKr0.00000100.000183.7980.0000840.00029
HydrogenH20.00000050.000052.0160.0000010.000003
XenonXe0.000000090.000009131.2930.0000120.00004
Average molar mass of air28.9647
  • 1 kg = 2.2046 lb

Air Density

The density of dry air can be calculated with the Ideal Gas Law

ρ = P / (R T) (1)

where

P = pressure (Pa)

Rair = 287.05 = individual gas constant [J/kg K]

T = absolute temperature [K]

Atomic Mass Of Oxygen 18


Example: The density of dry air at atmospheric pressure 101.325 kPa (101325 Pa) and 0 oC (= 273.15 K) can be calculated as

Atomic Mass Of Oxygen Vs Chlorine

ρ = 101325 [Pa] / (287.05 [J/kg K]*273.15 [K])

= 1.292 [kg/m3]

Water Vapor

Water vapor is almost always present in air. The content may vary and the maximum amount possible of water vapor in dry air depends on the temperature of the air.

Water vapor - H2O - is composed of one oxygen atom and two hydrogen atoms. Hydrogen is the lightest element with a molar mass of 1 g/mol, while oxygen has 16 g/mol. Thus, the water vapor atom has an molar mass of 18 g/mol, and water vapor is lighter than O2 with 32 g/mol and N2 with 28 g/mol.

Atomic Mass Of Oxygen

  • Note! Water vapor in air will dilute the other gases and reduce the total density of the mixture. Dry air is more dense than humid air!

The vapor in air may saturate to droplets when temperature is decreased or pressure is increased.

Atomic Mass Of Oxygen-18

Humid air containing water molecules as liquid - droplets - may be more dense than dry air or humid air containing water only as vapor.

Atomic Mass Of Oxygen Rounded

Related Topics

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Related Documents

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Amu

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