This mechanism has been proposed for the reaction between chloroform and chlorine. Step 1: Cl2(g) ⇌ — Kinetics Chemistry Question
Problem Context
This mechanism has been proposed for the reaction between chloroform and chlorine.
Step 1: Cl2(g) ⇌ 2Cl(g) fast
Step 2: CHCl3(g) + Cl(g) → CCl3(g) + HCl(g) slow
Step 3: CCl3(g) + Cl(g) → CCl4(g) fast
Write the stoichiometric equation for the overall reaction.
Model Answer
Cl2 + CHCl3 → CCl4 + HCl
Identify any reaction intermediates in this mechanism.
Model Answer
Cl and CCl3
Write the rate equation for the rate determining step.
Model Answer
Rate = k[CHCl3][Cl]
Show how the rate equation in c. can be used to obtain the rate law for the overall reaction.
Model Answer
Because this step is at equilibrium, we can express the [Cl] in terms of [Cl2] by looking at the equilibrium constant expression. K = [Cl]2 / [Cl2] so [Cl]2 = K[Cl2] and [Cl] = K1/2[Cl2]1/2. Thus by substituting we get the overall expression to be: Rate = k[CHCl3][Cl2]1/2
If the concentrations of the reactants are doubled, by what ratio does the reaction rate change? Explain.
Model Answer
If [CHCl3] and [Cl2] are doubled, rate will increase by (2)•(2)1/2 = 2.83 times.