What is R in the mathematical expression of the ideal gas law?

1 Answer
May 25, 2014

The units of Ideal gas law constant is derived from equation PV = nRT?

Where the pressure - P, is in atmospheres (atm) the volume - V, is in liters (L) the moles -n, are in moles (m) and Temperature -T is in Kelvin (K) as in all gas law calculations.

The R value is the Ideal Gas Law Constant which we derive through algebraic reconfiguration we end up with Pressure and Volume being decided by moles and Temperature, giving us a combined unit of
#(atm x L) / (mol x K)#. the constant value then becomes 0.0821 #(atm(L))/(mol(K))#

If you choose not to have your students work in standard pressure unit factor, you may also use: 8.31 #(kPa(L))/(mol(K))# or 62.4 #(Torr(L))/(mol(K))#.

Temperature must always be in Kelvin (K) to avoid using 0 C and getting no solution when students divide.

There is a variation of the ideal gas law that uses the density of the gas with the equation PM = dRT

Where M is the Molar Mass in #g/mol# and d is the Density of the gas in #g/L#.

Pressure and Temperature must remain in the units atm and K and the Gas Law Constant remains R = 0.0821 #((atm) L) / ((mol) K)#.

I hope this is helpful.