Question:

The compressibility factor $(Z)$ of one mole of a van der Waals gas of negligible $�a�$ value is

Updated On: Jul 28, 2024
  • $1$
  • $\frac{bp}{RT}$
  • $1+\frac{bp}{RT}$
  • $1-\frac{bp}{RT}$
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is C

Solution and Explanation

van der Waals' equation is
$\left(p+\frac{a}{V^{2}}\right)(V-b)=R T\,\,\,$(for 1 mole)
If $a$ is negligible, $p+\frac{a}{V^{2}} \approx p$
$p(V-b)=R T $
$\Rightarrow p V-p b=R T $
or $\frac{p V}{R T}-\frac{p b}{R T}=1 $
$\Rightarrow \frac{p V}{R T}=1+\frac{p b}{R T}$
Was this answer helpful?
0
0

Concepts Used:

Van Der Waals Equation

Van der Waals equation is an equation relating the relationship between the pressure, volume, temperature, and amount of real gases.

Read More: Derivation of Van Der Waals Equation

Derivation of Van der Waals equation:

For a real gas containing ‘n’ moles, the equation is written as

Where, P, V, T, n are the pressure, volume, temperature and moles of the gas. ‘a’ and ‘b’ constants specific to each gas.

Where,

Vm: molar volume of the gas

R: universal gas constant

T: temperature

P: pressure

V: volume

Thus, Van der Waals equation can be reduced to ideal gas law as PVm = RT.

The equation can further be written as;

  1. Cube power of volume:
  2. Reduced equation (Law of corresponding states) in terms of critical constants:

Units of Van der Waals equation Constants

a: atm lit² mol-²

b: litre mol-¹