1. Tardigrade
  2. Question
  3. Chemistry
  4. Bond dissociation energies of H2, Cl2 and HCl(g) are 104, 58 and 103 kcal mol-1 respectively. Calculate the enthalpy of formation of HCl gas.

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Q. Bond dissociation energies of $H_2$, $Cl_2$ and $HCl_{(g)}$ are $104$, $58$ and $103\, kcal\, mol^{-1}$ respectively. Calculate the enthalpy of formation of $HCl$ gas.

Thermodynamics

Solution:

$\frac{1}{2}H_{2}+\frac{1}{2}Cl_{2}\to HCl$
$\Delta H = \frac{1}{2}\times104 + \frac{1}{2}\times 58 - 103 = -22\,kcal$