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प्रश्न
What is pseudo first order reaction? Give one· example of it.
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उत्तर
A reaction which has higher order true rate law but experimentally found to behave as first order are called pseudo first order reaction.
e.g. `C_12H_22O_(11(aq))+H_2OrarrC_6H_12O_6+C_6H_12O_6`
Sucrose Glucose fractose
is an example of pseudo first order reaction, because water takes part in the reaction the true rate law
rate = k'[C12H22O11][H2O]
indicates that the reaction must be second order. Similarly to the hydrolysis of ester,[H2O] is constant and
the rate law became
rate=k[C12H22O11]
Thus, the second order true law is converted, to first order rate law.
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संबंधित प्रश्न
Define “zero order reaction”.
A reaction is second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentrations of both A and B are doubled?
Write molecularity of the following reaction:
2NO(g)+O2(g)→2NO2(g)
The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume :
SO2Cl2 (g) → SO2 (g) + Cl2 (g)
| Experiment | Time/s–1 | Total pressure/atm |
| 1 | 0 | 0.4 |
| 2 | 100 | 0.7 |
Calculate the rate constant.
(Given : log 4 = 0.6021, log 2 = 0.3010)
The conversion of molecules X to Y follows second order kinetics. If concentration of X is increased to three times how will it affect the rate of formation of Y?
From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.
\[\ce{3NO_{(g)} -> N2O_{(g)}}\] Rate = k[NO]2
From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.
\[\ce{CH3CHO_{(g)} -> CH4_{(g)} + CO_{(g)}}\] Rate = k [CH3CHO]3/2
From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.
\[\ce{C2H5Cl_{(g)} -> C2H4_{(g)} + HCl_{(g)}}\] Rate = k [C2H5Cl]
For the reaction:
\[\ce{2A + B → A2B}\]
the rate = k[A][B]2 with k = 2.0 × 10−6 mol−2 L2 s−1. Calculate the initial rate of the reaction when [A] = 0.1 mol L−1, [B] = 0.2 mol L−1. Calculate the rate of reaction after [A] is reduced to 0.06 mol L−1.
A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is doubled?
A reaction is first order in A and second order in B. How is the rate affected on increasing the concentration of B three times?
For a reaction R ---> P, half-life (t1/2) is observed to be independent of the initial concentration of reactants. What is the order of reaction?
The decomposition of N2O5(g) at 320K according to the following equation follows first order reaction:
`N_2O_(5(g))->2NO_(2(g))+1/2O_(2(g))`
The initial concentration of N2O5(g) is 1.24 x 10-2 mol. L-1 and after 60 minutes 0.20x10-2 molL-1. Calculate the rate constant of the reaction at 320K.
Write the principle behind the following methods of refining:
Hydraulic washing
Define the following terms:
Half-life period of reaction (t1/2).
What is the order of a reaction which has a rate expression; Rate = `"k"["A"]^(3/2)["B"]^1`?
Consider a first order gas phase decomposition reaction given below :
\[\ce{A(g) -> B(g) + C(g)}\]
The initial pressure of the system before decomposition of A was pi. After lapse of time ‘t’, total pressure of the system increased by x units and became ‘pt’ The rate constant k for the reaction is given as ______.
Which of the following statements is not correct about order of a reaction.
Why molecularity is applicable only for elementary reactions and order is applicable for elementary as well as complex reactions?
Why can we not determine the order of a reaction by taking into consideration the balanced chemical equation?
Match the graph given in Column I with the order of reaction given in Column II. More than one item in Column I may link to the same item of Column II.
| Column I | Column II | |
| (i) |  |
|
| (ii) |  |
(a) 1st order |
| (iii) |  |
(b) Zero-order |
| (iv) |  |
Use Molecular Orbital theory to determine the bond order in each of species, [He2j+ and [He2]2+?
A catalyst in a reaction changes which of the following?
In the presence of a catalyst, the heat evolved or absorbed during the reaction.
For a reaction \[\ce{Cl2l(g) + 2No(g) -> 2NaCl(g)}\] the rate law is expressed as rate= K[Cl2] [No]2 what is the order of the reaction?
The rate constant for the reaction \[\ce{2H2O5 -> 4NO2 + O2}\] is 30 × 10–5 sec–1. if the rate is 204 × 10–5 mol L–1 S–1, then the concentration of N2O5 (in mol–1) is-
A drop of solution (volume 0.05 ml) contains 3.0 × 10-6 mole of H+. If the rate constant of disappearance of H+ is 1.0 × 107 mole l-1s-1. It would take for H+ in drop to disappear in ______ × 10-9s.
For a chemical reaction starting with some initial concentration of reactant At as a function of time (t) is given by the equation,
`1/("A"_"t"^4) = 2 + 1.5 xx 10^-3` t
The rate of disappearance of [A] is ____ × 10-2 M/sec when [A] = 2 M.
[Given: [At] in M and t in sec.]
[Express your answer in terms of 10-2 M /s]
[Round off your answer if required]
Assertion (A): Order of reaction is applicable to elementary as well as complex reactions.
Reason (R): For a complex reaction, molecularity has no meaning.
