Question

At low pressure, the Vander Waal's equation is reduced to.

• A. $Z = \frac { p V _ { m } } { R T } = 1 - \frac { a p } { R T }$
• B. $Z = \frac { p V _ { m } } { R T } = 1 + \frac { b } { R T } p$
• C. $p V _ { m } = R T$
• D. $Z = \frac { p V _ { m } } { R T } = 1 - \frac { a } { R T }$

Answer 1

Answer: (A)

$Z = \frac { p V _ { m } } { R T } = 1 - \frac { a p } { R T }$

Answer 2

When pressure is low $\left[ P + \frac { a } { V ^ { 2 } } \right] ( V - b ) = R T$

or $P V = R T + P b - \frac { a } { V } + \frac { a b } { V ^ { 2 } }$ or $\frac { P V } { R T } = 1 - \frac { a } { V R T }$

$\left( \because \frac { P V } { R T } = Z \right)$