Question

Enthalpy change for the reaction, 4 H(g) → 2H2 (g)
is -869.6 kJ. The dissociation energy of H-H
bond is
[AIPMT (Prelims)-2011]

(1) + 217.4 kJ
(2) - 434.8 kJ
(3) - 869.6 kJ
(4) + 434.8 kJ​

Answer 1

Explanation:

$\sf 4{H}_{g} \longrightarrow 2{{H}_{2}}_{g} \: \: \: \: \: \: \Delta H = - 869.6 KJ \: {mol}^{-1} \\ \\ \sf Reversing \:the\:reaction \: \Delta H \:changes \:it's \:sign \\ \\ \sf 2{{H}_{2}}_{g} \longrightarrow 4{H}_{g} \:\:\:\:\:\: \Delta H = 869.6 KJ \: {mol}^{-1} \\ \\ \sf Dividing \: the \:equation \: by \: 2 \\ \\ \sf {{H}_{2}}_{g} \longrightarrow H -- H \: \:\:\:\:\: \Delta H = 869.6/2 = 434.8 kJ\:{mol}^{-1} \\ \\ \sf This \:the\: reaction\:of\: dissociation\:of\:{H}_{2} \:and\: \Delta H \:for\:this\:reaction \:is\:called\:bond\: dissociation\:energy \\ \\ \sf So\:correct\:choice\:is\:option \: (4)$

❣️NIRANJAN45❣️

Answer 2

Answer:

-869.6 kJ

Explanation:

enthalpy change for the reaction ,4H(g)_2H2(g) is -869.6 kJ. The dissociation of energy of H-H bond is solution :The dissociation energy of H-H bond is =869.62=434.8kJ