Consider the following three step mechanism for a reaction
Cl2 > 2Cl Fast
Cl+CHCl3 > HCl+CCl3 Slow
Cl+CCl3 > CCl4 Fast
What is the predicted rate law? How do you do it? The answer is rate=K[Cl2]^.5 [CHCl3]
The elemntary reaction steps and their rates law are:
1) Cl₂ ↔ 2Cl
=> r₁ = k₁₊∙[Cl₂] - k₁₋∙[Cl]² (fast) [ reversible
reaction]
2) Cl + CHCl₃ → HCl + CCl₃
=> r₂ = k₂∙[Cl]∙[CHCl₃] (slow)
3) CCl₃ + Cl → CCl₄
=> r₃ = k₃∙[Cl]∙[CCl₃] (fast)
Overall reaction is given by
CHCl₃ + Cl₂ → CCl₄ + HCl
The overall rate is determined by the slowest step, reaction
2):
r_overall = k₂∙[Cl]∙[CHCl₃]
This rate law contains concentration of intermediate Cl, which need
to be eliminated.
Since reaction1 is a fast reversible reaction, you can consider to
be permanently at equilibrium. That means
r₁ = k₁₊∙[Cl₂] - k₁₋∙[Cl]² = 0
<=>
k₁₊∙[Cl₂] = k₁₋∙[Cl]²
Use the last relation to express [Cl] in terms of reactant
[Cl₂]
[Cl] = √( (k₁₊/k₁₋)∙[Cl₂] )
substitute to overall rate law:
r_overall = k₂∙√( (k₁₊/k₁₋)∙[Cl₂] )∙[CHCl₃]
= k ∙√[Cl₂]∙[CHCl₃]
= k [Cl2]^0.5 [ CHCl3]
Consider the following three step mechanism for a reaction Cl2 > 2Cl Fast Cl+CHCl3 > HCl+CCl3...
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) [CHCl3]1/2 M) [CCl3]2 B) [Cl2] H) [CCl3]1/2 N) [HCl]2 C) [Cl] I) [HCl]1/2 O) [Cl2]2 D) [CHCl3] J) [Cl2]1/2 P) [Cl]2 E)...
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) [Cl2]1/2 M) [CHCl3]2 B) [CCl3] H) [Cl]1/2 N) [CCl3]2 C) [HCl] I) [CHCl3]1/2 O) [HCl]2 D) [Cl2] J) [CCl3]1/2 P) [Cl2]2 E)...
1. The rate of formation of carbon tetrachloride from chloroform, CHCl3(g) + Cl2(g) => CCl4(g) + HCl(g) is first order in CHCl3 and half order in Cl2. Which step of the proposed mechanism must be slow in order to agree with this rate law? 1. Cl2(g) => 2 Cl(g) 2. Cl(g) + CHCl3(g) => HCl(g) + CCl3(g) 3. CCl3(g) + Cl(g) => CCl4(g) 1. 1 2. 2 3. 3 2. The proposed mechanism for a reaction is Cl2 =>...
For the reaction mechanism shown, identify the intermediates(s) Cl2(gas)<------>2Cl(gas) CHCl3(gas)+ Cl(gas)<------>HCL(gas)+CCl3(gas) CCl3(gas)+Cl(gas)<------>CCl4(gas)
consider the aqueous reaction of Cl2 + H2S -> S + 2HCL . It may happen by the following mechanism 1: Cl2-> <- 2Cl fast 2: Cl+H2S -> <- HCl + HS fast 3: HS +Cl --> --< HCl + S slow DERIVE a rate law for overall reaction using the given mechanism and rate determining step without using intermediates in the rate law.
The proposed mechanism for a reaction is Cl2 => Cl+ + Cl- Slow Cl- + H2S => HCl + HS- Fast Cl+ + HS- => HCl + S Fast Which of the following would be a rate law for the reaction? A. rate = k[Cl2] B. rate = k[Cl2][H2S] C. rate = k[Cl2]1/2[H2S] D. rate = k[Cl-][H2S] E. rate = [Cl+][Cl-]
5. Consider this 2-step mechanism for a reaction. NO2(g) + Cl2(g) k1 ClNO2 (g) + Cl(g) Slow NO2(g) + Cl(g) k2 ClNO2(g) Fast a. What is the overall reaction? b. Identify the intermediates in the mechanism. c. What is the predicted rate law?
Consider the following two-step mechanism for a reaction: NO2(g)+Cl2(g)→ClNO2(g)+Cl(g)Slow N O 2 ( g ) + C l 2 ( g ) → C l N O 2 ( g ) + C l ( g ) S l o w NO2(g)+Cl(g)→ClNO2(g)Fast a)What is the overall reaction? Express your answer as a chemical equation. Identify all of the phases in your answer. b)Identify the intermediates in the mechanism. Check all that apply. Check all that apply. NO2(g), ClNO2(g), Cl2(g) ,Cl(g)...
Consider the reaction 2 NO + Cl2 → 2 NOCI A possible mechanism is: Cl2 ⇄ 2 Cl (fast) Cl + NO → NOCl (slow) If this is correct, the rate law will be: A. rate = k [NO]0.5[Cl] B. rate = k [NO]2[Cl2] C. rate = k [NO][Cl2] D. rate = k [NO][Cl]2 E. rate = k [NO][Cl2]0.5
A possible mechanism for the reaction of chlorine gas and chloroform to produce carbon tetrachloride and hydrogen chloride is given below. Cl2(g) ⇄ 2 Cl(g) Cl(g) + CHCl3(g) → HCl(g) + CCl3(g) Cl(g) + CCl3(g) → CCl4(g) What is/are the intermediate(s) in this mechanism? Cl only both Cl and CCl3 CCl3 only HCl only