How to calculate the molar mass?

How to calculate the molar mass of a gas, with values for volume, pressure and temperature?

• "What is the molar mass of a gas if 0.675g of the gas occupies 250ml (volume) at 152000 Pa (pressure) and 25.0⁰C (degrees Celcius)?" The correct answer (from my Chemistry textbook) is 44.0g mol-1.

• Answer:

  Yes, you are supposed to use the Ideal Gas Law. Basically in order to use the formula, you need to express everything in SI units. So: 250ml = 0.25dm^3 25.0 degrees Celsius = 298 Kelvin Now for the working: n= pV/RT = (152000*0.25)/(298R) = 15.33672595 Since n= m/M M= m/n = (0.675/15.33672595)*1000 = 44.01200113g mol-1 = 44.0g mol-1 P.s: Yes, the multiplication at the end was so that it can be expressed in grams. The SI unit for mass is kg so the initial calculation was also in kg.