MCQ
The bond dissociation enthalpy of $H_2(g)$ and $N(g)$ are $436\  kJ\ mol^{-1}$ and $940\  kJ\ mol^{-1}$ and enthaply of formation of $NH_3$ is $- 45\  kJ\  moI^{-1}$ . The enthaply of atomisation of $NH_3$ is.....$kJ\  mol^{-1}$
  • A
    $- 1079$
  • B
    $- 1169$
  • C
    $1079$
  • $1169$

Answer

Correct option: D.
$1169$
d
$-45=\frac{1}{2} \times 940+\frac{3}{2} \times 436-\Delta_{\mathrm{a}} \mathrm{H}$

$\Delta_{\mathrm{a}} \mathrm{H}=654+470+45=1169 \,\mathrm{kJ}\, \mathrm{mol}^{-1}$

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