Expert: Kevin - 5/16/2008

Question
Hi.Could U please tell me why we show the universal gas constant by "R" ? It is very important to me.
Thanks,
A.Z

Answer
Hi Azadeh

Generally speaking the person who first publishes a set of equations gets to choose what letters to use for various constants and variables and defines them in the text. Over time certain letters become clearly associated with certain constants or variables. For example T = temperature, P = pressure, V = volume, Pi =3.1415926 etc.
Over time these get fixed and codified and become internationally accepted by for example IUPAC. Then people only use these constants in their fixed context. However, they may be used for something else as long as it is defined in the text.

The first use of "R" as the gas constant was chosen by the French Physicist B.P.E. Clapeyron when he published his work on ideal gases in 1834 and it seems to have stuck.

I hope this helps.

Best wishes
Kevin