How to write air?

[dr-jerry-katzman]

Hello my name is DR Jerry Katzman and I was wondering how do you write air as a composition of the elements?
Thank you for your help.

[sparky-the-lab-rat]

Air composition is normally expressed as a percentage, the following constituents make up 99.998% of air::

N2 --78.084%
O2 --20.947%
Ar --0.934%
CO2 --.033 %

There are other trace compounds in air, but they range from trace levels to ~18 ppm

Temperature and pressure affect the molar concentrations of each constituent, so the following values are only applicable under standard temperature and pressure conditions. The affect of temperature and pressure on concentrations can be determined using the ideal gas law:

PV=nRT

P= pressure (atm)
V= volume (L)
n= moles of gas (mol)
R= gas constant (L*atm*K^-1*mol^-1)
T= Temperature (K)

There are different values for R, but temperature (K) and volume (L) must be converted to absolute values.