A mole of CCl4 vapours at 77∘ C occupies a volume of 36.0 L.If vanderwaals constants are a=20.39L2 atm mol−2 and b=0.1383 L mol−1 calculate the compressibility factor Z under (a) low pressure region and (b) high pressure region.
The values of compressibility factor Za and Zb respectively are:
Za= 0.98, Zb =1.004
Under (a) Za= 0.98
Under (b) Zb= 1.004
Option b
a)Under low pressure region,the molar volume is high, so Vm−b≈Vm.The following equation.
(p+aV2m)(Vm−b)=RT
Then becomes pVm+aVm=RT
So the compressibility factor is
b)Under high pressure p is high , so
P(Vm−b)=RT⇒p=RTVm−b
Now, the compressibility factor is
Z=pVmRT=VmVm−b=11−(bVm)=11−(0.13835)=1.004