Non ideal Gases

Question

A 1.18-mol sample of krypton gas is maintained in a 0.662-L container at 306 K. Calculate the pressure of the gas using both the ideal gas law and the van der Waals equation (van der Waals constants for Kr are a = 2.32 L²atm/mol² and b = 3.98×10^-2 L/mol).

Pideal gas equation =	atm
Pvan der Waals  =	atm

Answer 1

Ideal gas law:

PV = nRT

P = ?

V = 0.662 L

n = 1.18 mols

R = 0.0821 Latm/Kmol

T = 306K

P = nRT/V = (1.18)(0.0821)(306) / 0.662

P = 44.8 atm

van der Waals equation:

(P + n²a/V²) (V - nb) = nRT

P = ?

n = 1.18 mols

a = 2.32 L²atm/mol²

V = 0.662 L

b = 3.98x10^-2 L/mol

P = nRT/V-nb - n²a/V² = [(1.18)(0.0821))(306) / [0.662 - (1.18 * 3.98x10^-2] - (1.18)²(2.32)/(0.662)²

P = (29.64 / 0.6151) - 7.371 = 48.19 - 7.37

P = 40.8 atm

(As always, please check and double check the math)