The pressure of the gas N2O4 using an ideal gas equation is, p=
nRT
V
Substitute the given value in above expression. p=
18.4×0.083×400
1×92
=6.64 bar At equilibrium condition, the pressure of N2O4 is p−pi and thepressure of NO2 is 2pi The total pressure at an equilibrium condition is given as, pT=p−pi+2pi pT=p+pi pi=10.64−6.64 =4‌bar The value of equilibrium constant is, Kp=