(Solved): Bond Dissociation Energies of Relevant Bonds \( (\mathrm{kJ} / \mathrm{mol}) \) Two possible react ...

Bond Dissociation Energies of Relevant Bonds \( (\mathrm{kJ} / \mathrm{mol}) \) Two possible reactions of chlorine with ethane are shown below: (A) \( \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}+\mathrm{Br}-\mathrm{Br} \stackrel{\text { light }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br}+\mathrm{HBr} \) (B) \( \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}+\mathrm{Br}-\mathrm{Br} \stackrel{\text { light }}{\longrightarrow} 2 \mathrm{CH}_{3} \mathrm{Br} \) (a) Deduce which of these reactions is favored based on calculations using the data in the Table. Explain any assumptions in your calculations. These are simple calculations. Calculators are not needed. Show your calculations and explain your reasoning. ( \( 3 \mathrm{pts}) \) (b) Assuming that the two reactions shown in part (a) follow a radical chain mechanism complete the mechanisms for both reactions by filling in the missing information in the mechanism shown. ( \( 5 \mathrm{pts}) \) Reaction A: \( \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}+\mathrm{Br}-\mathrm{Br} \stackrel{\text { light }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br}+\mathrm{HBr} \) Initiation step: \( \quad \mathrm{Br}-\mathrm{Br} \longrightarrow 2 \mathrm{Br}^{\circ} \quad \) (show arrows) Propagation step 1: \( \mathrm{CH}_{3}-\mathrm{CH}_{3}+\mathrm{Br}^{\bullet} \longrightarrow \quad \) (show arrows and products) Propagation step 2: \( \quad \) write out reaction and mechanism for step 2 Reaction B: \( \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}+\mathrm{Br}-\mathrm{Br} \stackrel{\text { light }}{\longrightarrow} 2 \mathrm{CH}_{3} \mathrm{Br} \) Initiation step: \( \quad \mathrm{Br}-\mathrm{Br} \longrightarrow 2 \mathrm{Br}^{\circ} \quad \) (show arrows) Propagation step 1: \( \mathrm{CH}_{3}-\mathrm{CH}_{3}+\mathrm{Br}^{\bullet} \longrightarrow \mathrm{CH}_{3}-\mathrm{Br}+\mathrm{CH}_{3} \) (show arrows) Propagation step 2: \( \quad \) write out reaction and mechanism for step 2