Question

What is the bond energy of $Cl-Cl$ bond in the reaction ${\left(CH\right)}_4(g)+{\left(Cl\right)}_2(g)\to {\left(CH\right)}_{3}Cl(g)+HCl(g)$ which has $\Delta H=-25kcal$ .
Data:

1. Bond energy of $C-Cl$ = $84kcal$
2. Bond energy $H-Cl$ = $103kcal$ .
3. Bond energies of $C-H$ and $Cl-CI$ bonds are in the ratio $x:y$ . If $x:y=9:5$ .

• A. $70kcal$
• B. $80kcal$
• C. $67.85kcal$
• D. $57.85kcal$

Answer 1

Answer: (D)

The reaction
$-25=36a+5a-(84+27a+103)$
$162=14a$
$\Rightarrow a=11.57$
$\Rightarrow E_{C1-a}=5\times 11.57=57.85k$ cal