Question

13.0 moles of gas are in a 7.00 L tank at 20.5 ∘C . Calculate the difference in pressure between methane and an ideal gas under these conditions. The van der Waals constants for methane are a=2.300L2⋅atm/mol2 and b=0.0430 L/mol.

Express your answer with the appropriate units.

Answer 1

The van der Waals equation gas molecules
(P +n2a/v2 )(V - nb) = nRT
for methane gas

(P + 132 X 2.3/(7)2)(7-13X0.0430) = 13 X0.0821 X 293.5 T=273+20.5=293.5K, R = 0.0821 liter·atm/mol·K

(P + 7.9326) X 6.441 = 313.25255

P = 48.6341484 - 7.9326 = 40.7015 atm.

for ideal gas the equation PV = nRT

P X 7 = 13 X 0.0821 X 293.5

P =44.75036 atm

the difference in pressure between methane and an ideal gas under these conditions is = 40.7015 atm - 44.75036 atm = 4.0488 atm