The enthalpy of formation of ethane ( C 2 H 6 ) from ethylene by addition of hydrogen where the bond-energies of C − H , C − C , C = C , H − H are 414 kJ , 347 kJ , 615 kJ and 435 kJ respectively

Question

The enthalpy of formation of ethane ( C 2 ​ H 6 ​ ) from ethylene by addition of hydrogen where the bond-energies of C − H , C − C , C = C , H − H are 414 kJ , 347 kJ , 615 kJ and 435 kJ respectively is kJ

TestHub · Accepted Answer

​ C 2 ​ H 4 ​ ( g ) + H 2 ​ ( g ) → C 2 ​ H 6 ​ ( g ) Δ H = BE ( C = C ) + 4 BE ( C − H ) + BE ( H − H ) − BE ( C − C ) − 6 BE ( C − H ) Δ H = BE ( C = C ) + BE ( H − H ) − BE ( C − C ) − 2 BE ( C − H ) = 615 + 435 − 347 − 2 × 414 = − 125 kJ ​

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