Question

Pick only the incorrect statement.

• A. for gas A, if a=0,the compressibility factor is linearly dependent on pressure.
• B. for gas B=0,if b=0,the compressibility factor is lineraly dependent on pressure.
• C. for gas C,$a\ne 0$,$b\ne 0$,it can be used to calculate a and b by giving lowest P value.
• D. slope for all three gases at high pressure is positive

Answer 1

Answer: (C)

for gas C,$a\ne 0$,$b\ne 0$,it can be used to calculate a and b by giving lowest P value.

Solution:- (C) for gas $C,a\ne 0,b\ne 0$, it can be used to calculate $a$ and $b$ by giving lowest $P$ value.

According to the real gas equation,

The constants '$a$' and '$b$' are Van der Waals constant for attraction and volume for a given gas.

• The '$a$' values for a given gas are measure of intermolecular forces of attraction. More are the intermolecular forces of attraction, more will be the value of a.
• For a given gas van der Waals constant of attraction '$a$' is always greater than van der Waals constant of volume '$b$'.
• The gas having higher value of '$a$' can be liquefied easily and therefore $H_2$ and $He$ are not liquefied easily.

According to this, for gas $A(Z>1),a=0$ and its dependence on $P$ is linear at all pressure and for gas $B(Z<1),b=0$ and its dependence on $P$ is linear at all pressure.

Also, at high pressure, the slope is positive for all real gases.