In gaseous reactions important for the understanding of the upper atmosphere ${{\rm{H}}_2}{\rm{O}}$ and ${\rm{O}}$ react bimolecularly to form two ${\rm{OH}}$ radicals. $\Delta H$ for this reaction is $72\;{\rm{kJ}}\;{\rm{ at}}\;500\;{\rm{K}}$ and ${E_a}$ is $77\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{ - 1}}$, then ${E_a}$ for the bimolecular recombination of two OH radicals to form ${{\rm{H}}_2}{\rm{O}}$ and ${\rm{O}}$ is:

$5\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{ - 1}}$

$3\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{ - 1}}$

$4\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{ - 1}}$

$7\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{ - 1}}$

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NEET UG CHEMISTRY MCQ: CHEMICAL KINETICS

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Application +4 | -1

In gaseous reactions important for the understanding of the upper atmosphere

{\mathrm{H}_2}\mathrm{O}

and

\mathrm{O}

react bimolecularly to form two

\mathrm{OH}

radicals.

\Delta H

for this reaction is

72\;\mathrm{kJ}\;\mathrm{ at}\;500\;\mathrm{K}

and

{E_a}

77\;\mathrm{kJ}\;\mathrm{mo}{\mathrm{l}^{ - 1}}

, then

{E_a}

for the bimolecular recombination of two OH radicals to form

{\mathrm{H}_2}\mathrm{O}

and

\mathrm{O}

is:

View answer and explanation

Correct option: C

5\;\mathrm{kJ}\;\mathrm{mo}{\mathrm{l}^{ - 1}}

Option C (5 kJ/mol) is correct because it is calculated by using the relationship between the activation energies of the forward and reverse reactions and the enthalpy change of the reaction.

NEET UG CHEMISTRY MCQ: CHEMICAL KINETICS

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