Question

Bond dissociation energy of $CH _{4}$ is $360\, kJ / mol$ and $C _{2} H _{6}$ is $620 \,kJ / mol$. 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

Answer: (C)

Dissociation energy of methane $=360 kJ mol ^{-1}$
$\therefore $ Bond energy of $C - H$ bond
$=\frac{360}{4}=90 kj$ Bond energy of ethane,
$1 r(C-C)+6(C-H)=620 kJ / mol$
$(C-C)+6 \times 90=620$
$(C-C)+540=620$
$C-C=620-540$
$C - C =80 kJ mol ^{-1} .$
Bond dissociation of $C-C$ bond $=80 kJ mol ^{-1}$.