Ideal Gas Equation

When dealing with Gas calcuations we use the Ideal as equation:

PV = nRT

P- Pressure - Pascales(Pa) - [1kpa = 1000 Pa]

V - Volume - m3 - [1m3 = 1000dm3] [1m3 = 1,000,000cm3]

n - No. of moles

R - Gas constant - 8.31 JK-1mole-1

T - Temperature - Kelvin(K) - [Celcius + 273]

At 273 K and 101000 Pa, 6.319 g of a gas occupies 2.00 dm3. Calculate the relative molecular mass of the gas. (Gas constant = 8.31)

Moles = Mass/Mr (so we substitude in)

PV=nRT     n=PV/RT    Mass/Mr=PV/RT     Mr=Mass/PV x RT

First put the volume in m3 - 2dm3/1000m3 = 0.002m3

Now put the numbers into the final equation

Mr= [6.319/(101000 x 0.002)] x (8.31 x 273)

Mr= 70.98