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Thermodynamics

# What is the bond dissociation energy of $HCl?( \Delta H_f^o\: of\: HCl(g), H(g), Cl(g) \: are\: -92.2, 217.7\: and\: 121\: kJ/mol$ respectively)

$\begin {array} {1 1} (a)\; -430.9kJ/mol & \quad (b)\; 430.9kJ/mol \\ (c)\;246.5kj/mol & \quad (d)\;-246.5kj/mol \end {array}$

$HCl(g) \rightarrow H(g) + Cl(g)$
Standard enthalpy change for this reaction, $\Delta H^o = \sum H_f^o$(products) $- \sum \Delta H_f^o$(reactants)
$= 217.7 + 121 – (-92.2) = 430.9\: kJ/mol$
Thus,$\Delta H^o_{H-Cl} = \Delta H^o = 430.9 \: kJ/mol$
Ans : (b)