If the bond energies of H − H , Br − Br , and H − Br are 433,192 and 364 kJ / mol − 1 respectively, the Δ H ∘ for the reaction H 2 ( g ) + Br 2 ( g ) → 2 HBr ( g ) is:

Question

If the bond energies of H − H , Br − Br , and H − Br are 433,192 and 364 kJ / mol − 1 respectively, the Δ H ∘ for the reaction H 2 ( g ) ​ + Br 2 ( g ) ​ → 2 HBr ( g ) ​ is:, − 261 kJ, + 103 kJ, + 261 kJ, − 103 kJ

MARKS App · Accepted Answer

H − H + Br − Br → 2 H − Br $ 433 + 192 = 625 ​ 2 = 728 ​ × 364 E n er g y ab sor b e d E n er g yre l e a se d N e t e n er g yre l e a se d =\Sigma \mathrm{H}_{\mathrm{R}}-\Sigma \mathrm{H}_{\mathrm{p}} =625-728=-103 \mathrm{~kJ}$. Related Theory Fluorine has high bond energy because it is smallest among these molecules so it is tightly bonded to other atoms due to greater nuclear charge.

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