A sample of gas has a mass of 38.8 mg . Its volume is 228 mL at a temperature of 55 ∘C and a pressure of 829 torr . Find the molar mass of the gas.
Volume of gas V=228ml =0.228L
Temperature of gas T=55℃=55+273=328K
Pressure of gas P =829torr =829/760=1.09atm
(As 760torr=1atm)
By ideal gas law PV=nRT
Where n is the number of moles of gas
R=0.0820Latm/molK
n=PV/RT
Therefore n=(1.09 atm×0.228L)/(0.0820 Latm/molK ×328K)
=9.24×10-3mol
Given mass of gas=38.8mg= 38.8×10-3g
Given mass/molar mass = number of moles of gas
Molar mass =given mass/number of moles
=38.8×10-3/9.24×10-3 =4.199g/mol
Thank you.