0.120g of an ideal gas was introduced into a gas syringe. The volume occupied by the gas at a pressure of 1.02x10^5 Pa and temperature 20 degrees was 49.3 cm^3. Calculate the molar mass of the gas.

The ideal gas law is PV=nRT, and we know that we can achieve the molar mass through the relationship of; n=m/mr. When using the ideal gas law it is essential that we use SI units before we begin plugging in the numbers. In this case the pressure is fine as needs to be in Pascals. The temperature needs to be converted from degrees into Kelvin by adding 273 (20+273). Volume needs to be in metres from cm^3 by dividing by 1000000 which leaves us with 0.0000493. In this R is a constant known as the gas constant and has a value of 8.31JK-1mol-1. When solving the equation for n=PV/RT we are left with a value of 2.07x10-3 mol. However the question asks for the molar mass and so we need to utilise the equation n=m/mr. Reaarranging leaves mr=mass/moles. We simply plug in the value for the mass that was given of 0.120 and our calculated moles value of 2.07x10-3, to give the answer of 58.1gmol-1