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Calculate the half-life of a first order reaction from the rate constant given below: 2 min−1 - Chemistry

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प्रश्न

Calculate the half-life of a first order reaction from the rate constant given below:

2 min−1

संख्यात्मक
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उत्तर

For a first order reaction,

Half life (t1/2) = `0.693/k`

= `0.693/2`

= 0.346 min

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अध्याय 3: Chemical Kinetics - Exercises [पृष्ठ ८६]

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एनसीईआरटी Chemistry Part 1 and 2 [English] Class 12
अध्याय 3 Chemical Kinetics
Exercises | Q 3.13 (ii) | पृष्ठ ८६

संबंधित प्रश्न

Derive the relation between half life and rate constant for a first order reaction


The rate constant for a first order reaction is 100 s–1. The time required for completion of 50% of reaction is _______.

(A) 0.0693 milliseconds

(B) 0.693 milliseconds

(C) 6.93 milliseconds

(D) 69.3 milliseconds


For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.


 A first order reaction takes 40 minutes for 30% decomposition. Calculate t1/2 for this reaction. (Given log 1.428 = 0.1548)


A first order reaction takes 23.1 minutes for 50% completion. Calculate the time required for 75% completion of this reaction.

(log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)


A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.

(log 2 = 0.3010)


The half-life for radioactive decay of 14C is 5730 years. An archaeological artifact containing wood had only 80% of the 14C found in a living tree. Estimate the age of the sample.


The experimental data for decomposition of N2O5.

\[\ce{2N2O5 -> 4NO2 + O2}\] in gas phase at 318 K are given below:

t/s 0 400 800 1200 1600 2000 2400 2800 3200
102 × [N2O5]/mol L−1 1.63 1.36 1.14 0.93 0.78 0.64 0.53 0.43 0.35
  1. Plot [N2O5] against t.
  2. Find the half-life period for the reaction.
  3. Draw a graph between log [N2O5] and t.
  4. What is the rate law?
  5. Calculate the rate constant.
  6. Calculate the half-life period from k and compare it with (ii).

The rate constant for the first order decomposition of H2O2 is given by the following equation:

log k = 14.34 − 1.25 × 10K/T. 

Calculate Ea for this reaction and at what temperature will its half-period be 256 minutes?


The half-life period of zero order reaction A → product is given by

(a) `([A]_0)/k`

(b) `0.693/k`

(c) `[A]_0/(2k)`

(d) `(2[A]_0)/k`


A first order reaction takes 10 minutes for 25% decomposition. Calculate t1/2 for the reaction.

(Given : log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021)


Show that the time required for 99% completion is double of the time required for the completion of 90% reaction.


Define half life of a reaction.


Half life (t1/2) and completion time (T) of the zero order reaction are- (K = 0.001 mol/litre/sec and a = 1 M.)


Which radioactive isotope would have the longer half-life 15O or 19O? (Given rate constants for 15O and 19O are 5.63 × 10–3 s–1 and k = 2.38 × 10–2 s–1 respectively.)


Observe the graph shown in figure and answer the following questions:


Write the relationship between k and t1/2 (half-life period)


Assertion (A): The half-life of a reaction is the time in which the concentration of the reactant is reduced to one-half of its initial concentration.

Reason (R): In first-order kinetics, when the concentration of reactant is doubled, its half-life is doubled.


The unit of rate constant of zero order reaction is ______.


Calculate the half-life of a first order reaction from the rate constant given below:

4 year−1


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