Question

1a) The activity coefficients า.-2.27 and 72-1041 were found for a methanol (1)-ethy acetate (2) system at 313.15 K and 0.2. Calculate the excess Gibbs energy in this mioxture. 1b) Using the van der Waals equation of state calculate the pressure and compressibility factor of a substance whose critical temperature is 800 K and critical pressure is 8.314 MPa, at a temperature of 1000K and a molar volume of 1100 cm3 mol- Pr ART

Answer 1

1a) The excess gibbs free energy is given by,

$G^{E}= RT\sum x_{i}ln\gamma _{i}$

where $\gamma _{i}$ = activity coefficient of i-th component, x_i = mole fraction of i-th component, R= universal gas constant, T=temperature of the system. x₁=0.2 so x₂= 1 - 0.2 = 0.8

putting the values,

G" = 8.31 JKー1mol-1 × 313. 1 5K × Ο.2m2.27+ 0.8/n 1.0411mol

= 509.93 J