Answer to Question #52137 in Physical Chemistry for palashkumarmura

Question

Which one following molecule will have different value of molar enthalpy of formation, one calculate using bond energy concept and other measured calorimetrically
1) C2H6
2) but-1,3-diene
3) 1, 4-cyclohexadiene
4) N2O

Answer 1

1) C₂H₆ H =-84.67 kj/mol H<0
2) but-1,3-diene H<0
3) 1, 4-cyclohexadiene H<0
Right answer 4) N2O. N₂O has molar enthalpy of formation H=81.55 kj/mol H>0