Explain rate datermining step?
Answers
Answer:
The rate determining step is the slowest step of a chemical reaction that determines the speed (rate) at which the overall reaction proceeds. The rate determining step can be compared to the neck of a funnel. The rate at which water flows through a funnel is limited/ determined by the width of the neck of the funnel and not by the rate at which the water is poured into the funnel. Like the neck of the funnel, the slow step of a reaction determines the rate of a reaction. Not all reactions have rate determining steps and has one only if one step is significantly slower than the other steps in the reaction.
Consider this reaction:
2NO2+F2⟶2NO2F,(3.2.3.1)
which occurs via this mechanism
elementary step 1:
NO2+F2⟶NO2F+F(slow)
elementary step 2:
NO+2F⟶NO2F(fast)
For elementary step 1 has a rate constant of k1 and for elementary step 2 it has a rate constant of k2. The slowest step in this mechanism is elementary step 1 which is our rate determining step. Looking at this mechanism I see Intermediates. Intermediates are molecules or elements that are found on the product of one step but are also located in the reactant of another step. In this case we have two intermediates NO2 and F.
The rate equation is derived by the slowest step in the reaction. When writing a rate equation you set up the equation by writing rate is equal to the rate constant of the slowest step times the concentrations of the reactant or reactants raised to there reaction order.