Question

Bond dissociation energy of `CH_(4)` si 360 kJ/mol and `C_(2)H_(6)` has 620 kJ mol. Then bond dissociation energy of C-C bond is :-
A. 170 kJ/mol
B. 50 kJ/mol
C. 80 kJ/mol
D. 220 kJ/mol

Answer 1

Correct Answer - C
`CH_(4(g))rarr C_((g))+4H_((g)) , Delta H=360 kJ//mol`
so, bond dissociation energy of one C - H bond
`=(360)/(4)=90` kJ/mol
`(H-overset(H)overset(|)underset(H)underset(|)(C )-overset(H)overset(|)underset(H)underset(|)(C )-H)C_(2)H_(6(g))rarr 2C_((g))+6H_((g)), Delta H=320 kJ mol`
`Delta H=(B.E.)_(R )-(B.E.)_(P)`
`620=[6xx(B.E.)_(C-H)+1xx(B.E.)_(C-C)]-O`
`620=6xx90+(B.E.)_(C-C)`
`therefore (B.E.)_(C-C)=80 kJ//mol`