Question

The critical temperature and pressure of chlorine gas are 146 °C
and 93.5 atm respectively. Calculate the value of van der Waals'
constant b.​

Answer 1

The critical temperature and critical pressure of chlorine gas are 146°C and 93.5 atm respectively.

To find : The value of Van der Waals' constant b is...

solution : we know,

critical temperature, $T_c=\frac{8a}{27Rb}$ ...(1)

critical pressure, $P_c=\frac{a}{27b^2}$ ...(2)

dividing equation (1) from (2) we get,

⇒$\frac{T_c}{P_c}=\frac{8b}{R}$

here, $T_c$ = 146° C = 146 + 273 = 419K

$P_c$ = 93.5 atm

R = 0.082 atm.L/mol/K

so, 419/93.5 = 8b/0.082

⇒b = 0.046 L/mol

Therefore the value of b is 0.046 L/mol (approx)