C-C sigma bond enthalpy of ethane is 397 KJ mol^(-1) and C-C pi-bond enthalpy in ethene is 284 kJ mol^(-1). So what is the bond enthalpy of double bond in kJ mol^(-1) in ethane ?

C-C sigma bond enthalpy of ethane is 397 KJ mol^(-1) and C-C pi-bond e

1.	C-C sigma bond enthalpy of ethane is 397 KJ mol^(-1) and C-C pi-bond enthalpy in ethene is 284 kJ mol^(-1). So what is the bond enthalpy of double bond in kJ mol^(-1) in ethane ?
Answer» 384 823 681 284 Solution :`C-C sigma + C - C PI` BONDS) = (C = C DOUBLE BOND enthalpy) `(397 + 284) = 681 kJ mol^(-1)`