JEE Main & Advanced Chemistry Thermodynamics / रासायनिक उष्मागतिकी Question Bank Topic Test - Thermodynamics and Thermochemistry (8-5-21)

The \[H-H\] bond energy is 430 kJ \[mol\] and \[Cl-Cl\] bond energy is \[240\,kJ\,mo{{l}^{-1}}.\,\,\Delta H\] for \[HCl\] is \[-90\,kJ\]. The \[H-Cl\] bond energy is about

A) \[180\,kJ\,mo{{l}^{-1}}\]

B) \[360\,kJ\,mo{{l}^{-1}}\]

C) \[213\,kJ\,mo{{l}^{-1}}\]

D) \[425\,kJ\,mo{{l}^{-1}}\]

Correct Answer: D

Solution :

[d] \[\frac{1}{2}{{H}_{2}}+\frac{1}{2}C{{l}_{2}}\to HCl,\,\,\,\Delta H=-90\,KJ\]

\[\therefore \Delta H=\frac{1}{2}{{E}_{H-H}}+\frac{1}{2}{{E}_{Cl-Cl}}\]

or \[-90=\frac{1}{2}\times 430+\frac{1}{2}\times 240-{{E}_{HCl}}\]

\[\therefore {{E}_{H-Cl}}=425\,kJ\,mo{{l}^{-1}}\].