In Ideal Gas Law, there's gas constant R that we need to use in the formula PV=nRT. There are times when we are given different units and we need to do conversioins and here are the proper units we use.
Since PV= nRT,
so R = PV/nT or we can say R equals (pressure × volume) / (amount of gas × temperature).
We know that temperature can be in Celcuius , Fahrenheit and Kelvin.
For pressure we use units like atm, kPa and mmHg (torr).
For volumes, we may use cm3, m3, L or ft3.
Basically we just swap the units in the R formula, and get the gas constants with proper units. Most often we use these two gas constant units:
R=8.314 L kPa K−1 mol−1
R = 62.36 L mmHg K−1 mol−1
R= 62.36 L torr K−1 mol−1