Compute Δ r G (in kJ mol − 1 ) for the reaction A ( ℓ , 1 atm , 300 K ) ⟶ A ( g , 1 atm , 300 K ) Given that: Δ H v a p at 400 K = 40 kJ mol − 1 , C p ( A , ℓ ) = 75 J K − 1 mol − 1 , C p ( A

Question

Compute Δ r ​ G (in kJ mol − 1 ) for the reaction A ( ℓ , 1 atm , 300 K ) ⟶ A ( g , 1 atm , 300 K ) Given that: Δ H v a p ​ at 400 K = 40 kJ mol − 1 , C p ​ ( A , ℓ ) = 75 J K − 1 mol − 1 , C p ​ ( A , g ) = 33 J K − 1 mol − 1 . ln ( 4/3 ) = 0.3 . The normal boiling point of liquid A is 400 K .

TestHub · Accepted Answer

At boiling point T b ​ = 400 K , Δ S v a p , 400 ​ = T b ​ Δ H v a p ​ ​ = 400 40000 ​ = 100 J K − 1 m o l − 1 Δ C p ​ = C p ​ ( g ) − C p ​ ( l ) = 33 − 75 = − 42 J K − 1 m o l − 1 Entropy at 300 K: Δ S 300 ​ = 100 + ( − 42 ) ln 400 300 ​ = 100 + ( − 42 ) ln 4 3 ​ = 100 + 12.6 = 112.6 J K − 1 m o l − 1 Enthalpy at 300 K: Δ H 300 ​ = 40 + ( − 42 ) ( 300 − 400 ) /1000 = 44.2 k J m o l − 1 Δ G = Δ H − T Δ S = 44.2 − 300 ( 0.1126 ) Δ r ​ G = 10.42 k J m o l − 1 ​

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