Question

The following mechanism has been proposed for the gas-phase reaction of chloroform (CHCl3) and chlorine. Cl2 ⇌ 2Cl (fast, reversible) Cl + CHCl3 → HCl + CCl3 (slow) Cl + CCl3 → CCl4 (fast) What rate law does this mechanism predict? (Choose from the list below and enter your answers in alphabetical order, e.g. ABC ). A)k G) [CCl3]1/2 M) [HCl]2 B) [Cl] H) [HCl]1/2 N) [Cl2]2 C) [CHCl3] I) [Cl2]1/2 O) [Cl]2 D) [CCl3] J) [Cl]1/2 P) [CHCl3]2 E) [HCl] K) [CHCl3]1/2 F) [Cl2] L) [CCl3]2

Answer 1

Answer:

Rate = K [CHCl₃] [Cl₂]⁰•⁵

Rate = ACI (from the list of options)

Explanation:

Cl₂ ⇌ 2Cl (fast, reversible)

Cl + CHCl₃ → HCl + CCl₃ (slow)

Cl + CCl₃ → CCl₄ (fast)

The rate determining step is the slow step

Hence

Rate = k [Cl] [CHCl₃]

Then, we can write the rate equations for the other elemestart steps

Step 1

rate = k₁ [Cl₂] = k₁' [Cl]²

[Cl] = √{(k₁/k₁')} √{[Cl₂]}

Substituting for [Cl] in the rate determining step

Rate = k [Cl] [CHCl₃]

= k√{(k₁/k₁')} √{[Cl₂]} [CHCl₃]

k√{(k₁/k₁') = K

Rate = K√{[Cl₂]} [CHCl₃]

Rate = K [CHCl₃] [Cl₂]⁰•⁵

Option A = K

Option C = [CHCl₃]

Option I = [Cl₂]⁰•⁵

Hence, Rate = ACI

Hope this Helps!!!