AP EAMCET202022 Sep 2020Evening ShiftChemistryThermodynamics (C)Actual
For the reaction, N ₂ O ₄(g) 2 NO ₂(g) , if dinitrogen tetroxide is 50 % dissociated at 60^ C , the standard free energy change at this temperature and 1 ~atm pressure is
Options
- A-367.8 ~kJ ~mol ⁻¹
- B-763.8 ~kJ ~mol ⁻¹
- C-867 ~kJ ~mol ⁻¹
- D-249 ~kJ ~mol ⁻¹
Correct answer
B. -763.8 ~kJ ~mol ⁻¹
Step-by-step solution
array ccc (b) & N ₂ O ₄(g) & NO ₂(g) t=0 & 1 ~mol & 0 t=t_ cq & (1-0.5) & 2(0.5) array Total number of moles =0.5+1=1.5 ~mol p_ N ₂ O ₄ = 0.5 1.5 1 ~atm = 1 3 ~atm and p_ NO ₂ = 1 1.5 1 ~atm = 1 1.5 ~atm According to law of chemical equilibrium, K_p= (p_ NO ₂ )^2 (p_ N ₂ O ₄ ) = ( 1 1.5 )^2 ( 1 3 ) =1.33 ~atm Apply, G^ =-2.303 R T K_p aligned G^ & =-2.303 (8.314) (333) (1.33) & =-763.8 ~kJ / mol aligned Hence, the correct option is (2).