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प्रश्न
Answer the following in brief.
Give one example and explain why it is pseudo-first-order.
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उत्तर
Example: Consider the hydrolysis of methyl acetate.
\[\ce{CH3COOCH3_{(aq)} + H2O_{(l)} -> CH3COOH_{(aq)} + CH3OH_{(aq)}}\]
The rate law is rate = k' [CH3COOCH3][H2O]
Explanation: The reaction was expected to follow the second-order kinetics, however, obeys the first order. The reason is that solvent water is present in such large excess that the change in its concentration is negligible compared to the initial one or its concentration remains constant. Thus [H2O] = constant = k''. The rate law becomes rate = k' [CH3COOCH3]k'' = k [CH3COOCH3]
where, k = k'k''
The reaction is thus of first order.
संबंधित प्रश्न
Answer the following in brief.
Obtain the relationship between the rate constant and half-life of a first-order reaction.
How will you represent first order reactions graphically.
Solve
The half-life of a first-order reaction is 1.7 hours. How long will it take for 20% of the reactant to react?
Time required for 100% completion of a zero order reaction is _______.
Write a mathematical expression for integrated rate law for zero-order reaction.
Assertion: rate of reaction doubles when the concentration of the reactant is doubles if it is a first-order reaction.
Reason: rate constant also doubles.
If 75% of a first order reaction was completed in 60 minutes, 50% of the same reaction under the same conditions would be completed in ____________.
The integrated rate law is a direct relationship between ____________ and ____________.
A first order reaction has a rate constant 0.00813 min-1. How long will it take for 60% completion?
What is the value of rate constant of first order reaction, if it takes 15 minutes for consumption of 20% of reactants?
The rate constant of a reaction has same units as the rate of reaction. The reaction is of ____________.
A first order reaction completes its 10% in 20 minutes, then the time required to complete its 19% is ____________.
The activation energy of a reaction is zero. Its rate constant at 280 K is 1.6 × 10-6 s-1, the rate constant at 300 K is ______.
What is the order of reaction if the unit of rate constant (k) is mol dm−3 s−1?
The integrated rate equation for first-order reaction, A → product, is ______.
If time required to decrease concentration of reactant from 0.8 M to 0.2 M is 12 hours, the half life of this first order reaction is ____________.
Which of the following represents the expression for `(3/4)^"th"` life of 1st order reaction?
For the first order reaction, plot of log10 [A]t against time 't' is a straight line with a negative slope equal to ____________.
The order of the reaction for which the unit of rate constant is s−1 is ____________.
For first order reaction the slope of the graph of log10 [A]t Vs. time is equal to ____________.
A first order reaction is 75% completed in 60 minutes, the time required for it's 50% completion is ____________.
Reaction given below follows first order kinetics:
\[\ce{2N2O2 -> 4NO2 + O2}\]
Calculate the rate constant of reaction if concentration of N2O2 is 0.05 M and rate of reaction is 1.5 × 10−6 mol L−1 s−1?
For a zero order reaction, the plot of [A]t vs t is linear. The slope of the line is equal to ____________.
In a reaction \[\ce{N2_{(g)} + 3H2_{(g)} -> 2NH3_{(g)}}\], if the rate of disappearance of N2(g) is 2.6 × 10−4 M/s, the rate of disappearance of H2(g) in M/s is ____________.
0.0210 M solution of N2O5 is allowed to decompose at 43°C. How long will it take to reduce to 0.0150 M?
(Given k = 6.0 × 10−4 sec−1)
For the first order reaction A → B, the rate constant is 0.25 s-1, if the concentration of A is reduced to half, the value of rate constant will be ________.
Which one of the following reactions is a true first-order reaction?
Which of the following is correct for a first-order reaction?
Half-life of a first order reaction is 30 minutes and initial concentration of reactant is 0.1 M.
What is half-life of the reaction if initial concentration of reactant is doubled?
