How do I convert 20 mm of gas to pascals?

[fcukniles]

i know this probably sounds really stupid but how do i convert 20mm of gas into pascals?
thnx

 

[faust9]

Pa has units of $N/m^2$ thus you need a little more info to convert 20mm of gas to pascals.

 

[Gamma]

$p = h \rho g$, when you use SI units in the RHS, P is in N/m^2. You need to know the density of the gas. g is the accelaration of gravity.