Question

what is the gas constant (R) for mm Hg?
8.31 is for atm
.08206 is for kPa
right?

Answer 1

You have them reversed.
0.08205 for atm
8.31 for kPa.

Answer 2

Then my teacher is messed up. So, for mm Hg it would be...?

By the way, Happy Halloween!!!!!

Answer 3

If you have pressure listed in mm mercury, change to atm by dividing by 760 mm/1 atm, then use R as 0.08206 L*atm/mol*K. If pressure is in kPa, use R as 8.3145 J/mol*K (kPa*L/mol*K).
Pressure in mm Hg may be changed to kPa by multiplying mm Hg x 0.13332 and using R of 8.1345 BUT I've not seen that done. You can try this yourself.
PV = nRT
Let's have P = 760 mm, V = 22.415 L, n = 1, R =?? and T = 273.15 K.

Solve for R.
R = PV/nT = (760/760)*22.415/1*273.15 = 0.08206

Let P = 101.325 kPa, V = 22.415 L, n = 1, R = ??, and T = 273.15 K.
R = 101.325*22.415/1*273.15 = 8.315

Let P = 760 mm, V = 22.415 L, n = 1, R = ?? and T = 273.15 K.
R = 760*22.415*0.13332/1*273.15 = 8.315

Here is a site that talks a little more about it but the conversion from mm Hg to kPa is not listed. http://en.wikipedia.org/wiki/Gas_constant