Which of the following is/are the chain termination step during photochlorination of ethane?
(1) $CH_{3} \dot{CH}_{2} + \dot{Cl} ⟶ CH_{3} - CH_{2} - Cl$
(2) $CH_{3} \dot{CH}_{2} + CH_{3} CH_{2} ⟶ CH_{3} CH_{2} CH_{2} CH_{3}$
(3) $\dot{Cl} + \dot{Cl} ⟶ Cl_{2}$
(4) $\dot{C} l + \dot{H} ⟶ HCl$

Question

Which of the following is/are the chain termination step during photochlorination of ethane?

(1) $CH_{3} \dot{CH}_{2} + \dot{Cl} ⟶ CH_{3} - CH_{2} - Cl$

(2) $CH_{3} \dot{CH}_{2} + CH_{3} CH_{2} ⟶ CH_{3} CH_{2} CH_{2} CH_{3}$

(3) $\dot{Cl} + \dot{Cl} ⟶ Cl_{2}$

(4) $\dot{C} l + \dot{H} ⟶ HCl$

TestHub · Accepted Answer

Explain Question:

Identifying radical combination steps that stop the chain reaction.

Concept:

Free Radical Halogenation (Chain Termination)

Solution:

Termination occurs when any two free radicals collide and combine to form a stable molecule,

effectively removing the reactive species from the cycle. In the photochlorination of ethane, the

available radicals are ethyl (CH₃CH₂) and chlorine (CI).

• Step 1: Ethyl radical + Chlorine radical forms chloroethane.

• Step 2: Two ethyl radicals form butane (an impurity).

• Step 3: Two chlorine radicals form chlorine gas.

• Step 4: This is incorrect because free hydrogen radicals (H) are not produced in this mechanism; HCl is formed via abstraction in the propagation step.

Final Answer: Option (C)

Chemistry - Hydrocarbon Question with Solution | TestHub

Options:

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