For most of us oldies, when we see this, we would probably like to use #R=0.0821*L*atm*K^-1*mol^-1#, where #1*atm-=101.3*kPa#. The current standard assumes a pressure of #100*kPa# as the standard condition (why the change? It was probably some old physical chemist with a bee in his bonnet, and the standard was changed just to satisfy this silly old bugger, and shut him up!). Units of atmospheres, and litres, are intuitively used by chemists, and we can vizualize a pressure of 1 atmosphere by a mercury column; #1*atm-=760*mm*Hg#.
Anyway, whichever standard you use, you have to be consistent, and apply the standard appropriately. And various values of #R# SHOULD be listed as supplementary material in every chemistry and fysics exam you sit.
