A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl_2...

Question:

A three-step mechanism has been suggested for the formation of carbonyl chloride:

Step 1: {eq}\rm Cl_2 \rightarrow 2 Cl {/eq}

Step 2: {eq}\rm Cl + CO \rightarrow COCl {/eq}

Step 3: {eq}\rm COCl + Cl_2 \rightarrow COCl_2 + Cl {/eq}

Which species is an intermediate in the mechanism?

A) {eq}\rm Cl {/eq}.

B) {eq}\rm CO {/eq}.

C) {eq}\rm COCl {/eq}.

D) {eq}\rm COCl_2 {/eq}.

Reaction Intermediate:

Reaction intermediate is always formed along with transition state.

The amount of reaction intermediate formed is always less than the transition state formed in the energy profile diagram.

Anything that appears on the product side of the first step and the reactant side of the second step must be canceled.

The canceled compound is known as the intermediate of that reaction.

For the given reaction mechanism:

{eq}\begin{align*} \rm Step\;1:\,C{l_2} \to 2Cl\\ \rm Step\;2:\;Cl + CO \to COCl\\ \rm Step\;3:\,COCl + C{l_2} \to COC{l_2} + Cl \end{align*}{/eq}

In the whole reaction mechanism, chlorine in step 2 is canceled by one chlorine in step one and reproduced in step 3, but COCl is entirely canceled in step 2 by step 1 COCl.

Thus compound that is canceled out entirely in the reaction is COCl it is the intermediate of the reaction.

Answer: The correct option is (c).

Chemical Kinetics, Reaction Rate Constant & Equilibrium Constant

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Chapter 16 / Lesson 7
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Chemical kinetics looks at the reaction rate of different chemical reactions. Learn about reaction rate constant and equilibrium constant, chemical reactions and reaction rates, and equilibrium.