Question

Bond energies of are 430 kJ $mol^{- 1}$ respectively. $\Delta H_{f}$ for HCl is 91 kJ $mol^{- 1}$ what will be tha bond energy of $H - - Cl?$

• A. 672 kJ
• B. 182 kJ
• C. 245 kJ
• D. 88 kJ

Answer 1

Answer: (C)

245 kJ

Answer 2

: $\frac{1}{2}H_{2} + \frac{1}{2}Cl_{2} \rightarrow HCl$

$\Delta H_{f}(HCl) = 91kJmol^{- 1},H - - H = 430kJmol^{- 1}$

$\mathrm { Cl } - \mathrm { Cl } = 242 \mathrm {~kJ} \mathrm {~mol} ^ { - 1 }$

$91 = 336 - B.E.(H - C)$

B.E. $( \mathrm { H } - \mathrm { Cl } )$= 336 – 91 = 245 kJ