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प्रश्न
For a reaction
\[\ce{2H2O2->[I^-][Alkaline medium]2H2O + O2}\]
The Proposed mechanism is given below:
(1) H2O2+I- → H2O+IO-(slow)
(2) H2O2+IO-→H2O+I-+O2(fast)
(i) Write the rate law for the reaction.
(ii) Write the overall order of a reaction.
(iii) Out of steps(1) and (2), which one is the rate-determining step?
उत्तर
Let us consider the problem:
\[\ce{2H2O2->[I^-][Alkaline medium]2H2O + O2}\]
In Some cases, the rate of reaction depends not only on the reactant but may also depend on the substance present as a catalyst. This is also seen in the above reaction. The rate of reaction depends on the slowest step in case of a complex reaction.
(1) \[\ce{H2O + I^- ->[slow]H2O + IO^- }\]
(2) \[\ce{H2O2 + IO^- ->[fast]H2O + I^- + O2}\]
(i) Rate law:
Rate =`-1/2("d"["H"_2"O"_2])/"dt"="k"["H"_2"O"_2]["I"^-]`
(ii) The overall order of reaction:
Rate = k[[H2O2] `["I"^-]`
Order = 1 + 1 = 2
(iii) Slowest step is the rate determining step. Hence, step 1 is rate determining step.
संबंधित प्रश्न
Which of the following statements regarding catalyst is FALSE?
____________ is used as a catalyst for the following reaction:
\[\ce{CO + \underset{\text{(Steam)}}{H2O} ⇌ CO2 + H2}\]
In the manufacture of ammonia by Haber's process, Al2O3 does not act as a catalyst but increases the activity of the catalyst. The role of Al2O3 can be best described as ____________.
Which of the following is a character of catalyst?
For a certain reaction large fraction of molecules has energy more than the threshold energy, yet the rate of reaction is very slow. Why?
Match the items of Column I and Column II.
| Column I | Column II | |
| (i) | Diamond | (a) short interval of time |
| (ii) | Instantaneous rate | (b) ordinarily rate of conversion is imperceptible |
| (iii) | Average rate | (c) long duration of time |
Match the items of Column I and Column II.
| Column I | Column II | |
| (i) | Mathematical expression for rate of reaction | (a) rate constant |
| (ii) | Rate of reaction for zero order reaction is equal to | (b) rate law |
| (iii) | Units of rate constant for zero order reaction is same as that of | (c) order of slowest step |
| (iv) | Order of a complex reaction is determined by | (d) rate of a reaction |
Describe how does the enthalpy of reaction remain unchanged when a catalyst is used in the reaction.
For the reaction 3A `rightarrow` 2B, rate of reaction `+ (d[B])/(dt)` is equal to ______.
For the reaction \[\ce{3A -> 2B}\], rate of reaction `-("d"["A"])/"dt"` is equal to ______.
