Question

How do you find density in the ideal gas law?

Answer 1

The density is determined by utilizing a variation of the ideal gas law where density and molar mass replace moles and volume.

The original ideal gas law uses the formula PV = nRT, the density version of the ideal gas law is PM = dRT, where P is pressure measured in atmospheres (atm), T is temperature measured in kelvin (K), R is the ideal gas law constant 0.0821 `(atm(L))/(mol(K))` just as in the original formula, but M is now the molar mass (`g/(mol)`) and d is the density (`g/L`).

By rearranging the formula to `(PM)/(RT) = d` the units of atm, mol and K will cancel and the value will be left with the `g/L` units for density.