The reaction obey I order with respect to ${{\rm{H}}_2}$ and ${\rm{ICl}}$ both ${{\rm{H}}_2}\left( {\rm{g}} \right) + 2{\rm{ICl}}\left( {\rm{g}} \right) \to 2{\rm{HCl}}\left( {\rm{g}} \right) + {{\rm{I}}_2}\left( {\rm{g}} \right)$ Which of the following mechanism is in consistent with the given fact? Mechanism$A:{{\rm{H}}_2}\left( {\rm{g}} \right) + 2{\rm{ICl}} \to 2{\rm{HCl}}\left( {\rm{g}} \right) + {{\rm{I}}_2}\left( {\rm{g}} \right)$ Mechanism$B:\left( {\rm{i}} \right){{\rm{H}}_2}\left( {\rm{g}} \right) + {\rm{ICl}}\left( {\rm{g}} \right)\xrightarrow{{Slow}}{\rm{HCl}}\left( {\rm{g}} \right) + {\rm{HI}}\left( {\rm{g}} \right)$ $\left( {{\rm{ii}}} \right){\rm{HI}}\left( {\rm{g}} \right) + {\rm{ICl}}\left( {\rm{g}} \right) \to {\rm{HCl}}\left( {\rm{g}} \right) + {{\rm{I}}_2}$

JEE CHEMISTRY MCQ: CHEMICAL KINETICS

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Analyzing +4 | -1

The reaction obey I order with respect to

{\mathrm{H}_2}

and

\mathrm{ICl}

both

{\mathrm{H}_2}\left( \mathrm{g} \right) + 2\mathrm{ICl}\left( \mathrm{g} \right) \to 2\mathrm{HCl}\left( \mathrm{g} \right) + {\mathrm{I}_2}\left( \mathrm{g} \right)

Which of the following mechanism is in consistent with the given fact?

Mechanism

A:{\mathrm{H}_2}\left( \mathrm{g} \right) + 2\mathrm{ICl} \to 2\mathrm{HCl}\left( \mathrm{g} \right) + {\mathrm{I}_2}\left( \mathrm{g} \right)

Mechanism

B:\left( \mathrm{i} \right){\mathrm{H}_2}\left( \mathrm{g} \right) + \mathrm{ICl}\left( \mathrm{g} \right)\xrightarrow{{Slow}}\mathrm{HCl}\left( \mathrm{g} \right) + \mathrm{HI}\left( \mathrm{g} \right)

\left( {\mathrm{ii}} \right)\mathrm{HI}\left( \mathrm{g} \right) + \mathrm{ICl}\left( \mathrm{g} \right) \to \mathrm{HCl}\left( \mathrm{g} \right) + {\mathrm{I}_2}

View answer and explanation

Correct option: D

B

only

Option C (

A

only) is correct because mechanism A is consistent with the rate law, while mechanism B is not, as its slow step would lead to a different rate law.