Chemistry
posted by Sally .
An experiment shows a 144mL sample of gas has a mass of 0.173g at a pressure of 720mmHg at a temperature of 31 degrees celsius. what is the molar mass of the sample of gas?

PV = nRT and solve for n = number of mols. Then n = grams/molar mass. You know n and grams, solve for molar mass.

I have done this and got 31.68 for the molar mass. I converted 720.mmHg to .947 atm. T is 304 degrees K. I came up with n=5.47*10^3. This gives me a molar mass of 31.63. I am being told this is incorrect. I am not sure where I am going wrong. Can you help me? L=.144