Question

Calculate deltaS for N₂ (1 bar, 298 K) --> N₂ (32 bar, 1500 K). Assume N₂ to be an ideal gas. C_P = 28.58 + 3.77 x 10^-3 T – 0.50 x 10⁵ T^-2 J K^-1 mol^-1

Answer 1

For n moles of ideal gas,

     

n =? (not given in question)

Let us take , n=1, for 1 mole of Ideal gas

Here, T₁ = 298 K, P₁ =1 bar, T₂ =1500 K, P₂ = 32 bar, R = 8.314 JK^-1 mol^-1,

C_P = 28.58 + 3.77 x 10^-3 T – 0.50 x 10⁵ T^-2 J K^-1 mol^-1 (C_p value is not clear).

Substituing the values of C_p, T₂, T₁, P₁ and P₂ in the equation below, we can get the value of S. Since C_p value looks strange

  

S = C_p ln (1500/298) -8.314 ln (32/1)

= C_p ln (5.0335) - 8.314 x ln (32)

=C_p x 1.616 - 28.814

Putting a correct value of C_p we can get S.