For the radical chain reaction below, the correct classification for step 2 and step 3 is, respectively,
Step 1: \( \text{Br}_2 + M \longrightarrow 2 \text{Br}^+ + M \)
Step 2: \( \text{Br}^+ + \text{H}_2 \longleftrightarrow \text{HBr} + \text{H}^+ \)
Step 3: \( \text{H}^+ + \text{Br}_2 \longrightarrow \text{HBr} + \text{Br}^+ \)
Step 1: \( \text{Br}_2 + M \longrightarrow 2 \text{Br}^+ + M \)
Step 2: \( \text{Br}^+ + \text{H}_2 \longleftrightarrow \text{HBr} + \text{H}^+ \)
Step 3: \( \text{H}^+ + \text{Br}_2 \longrightarrow \text{HBr} + \text{Br}^+ \)
Show Hint
- chain propagating, chain terminating
- chain branching, chain terminating
- chain propagating, chain propagating
- chain propagating, chain branching
The Correct Option is C
Solution and Explanation
Step 1: Understanding the radical chain reaction.
In a radical chain reaction, certain steps are classified as "chain propagating," "chain branching," or "chain terminating" based on how they affect the chain of reactions.
Step 2: Analyzing step 2 and step 3.
Step 2: The reaction \( \text{Br}^+ + \text{H}_2 \longleftrightarrow \text{HBr} + \text{H}^+ \) involves the consumption of radicals and the formation of new radicals, indicating a propagation of the chain reaction. Hence, step 2 is "chain propagating."
Step 3: The reaction \( \text{H}^+ + \text{Br}_2 \longrightarrow \text{HBr} + \text{Br}^+ \) also propagates the chain by generating more radicals. Thus, step 3 is "chain propagating."
Step 3: Conclusion.
Both steps 2 and 3 are chain propagating reactions, so the correct classification is (C).
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