The rate law for the reaction
2NO (g) + Cl2 (g) -> 2NOCl (g)
is given by
rate = k[NO][Cl2]
A mechanism involving the following steps has been proposed for the reaction:
NO (g) + Cl2 (g) -> NOCl2 (g)
NOCl2 (g) + NO (g) -> 2NOCl (g)
If this mechanism is correct, what does it imply about the relative rates of these two steps?
I think to solve this I have to find the rate determining step. I first thought the first step was the RDS because it has the right reactants. However, maybe it is the second one because the NOCl2 can be replaced by the NO and Cl2 from the first step and then the coefficients will be the same as in the overall reaction? PLEASE HELP!!!!!
sorry, i don't know.
According to the Liebig law of "Minimum" and the Blackman law of limiting factors, the rate of a multi-step reaction is determined by the step which has the lowest rate or velocity. This step is called the Rate-Determining or Rate-limiting Step.
sngxotrk lizrujk srnzk bzscqi znmsculw cyubql cxvwhid
It is the first step. Rate determinence depends solely on the reactants, so the first one works.
To determine the rate-determining step (RDS), we need to compare the proposed mechanism with the given rate law. The rate law for the overall reaction is:
rate = k[NO][Cl2]
Let's examine the two proposed steps in the mechanism and see if they match the rate law.
Step 1: NO (g) + Cl2 (g) -> NOCl2 (g)
Looking at this step, we can see that it involves the reactants NO and Cl2, but the product is NOCl2, not NOCl. Therefore, this step does not directly match the overall reaction and cannot be the rate-determining step.
Step 2: NOCl2 (g) + NO (g) -> 2NOCl (g)
This step involves NOCl2 and NO, and the product is 2NOCl, which matches the overall reaction. This step shows the formation of the desired product, NOCl, from the intermediate NOCl2. Therefore, this step can be considered as the rate-determining step.
If the proposed mechanism is correct, it implies that the second step is the rate-determining step, and the relative rates of the two steps can be determined by their respective rate constants.