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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

Define activation energy.

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प्रश्न

Define activation energy.

Define the following term:

Activation energy

Define energy of activation of a reaction.

व्याख्या
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उत्तर १

Activation energy is the lowest energy necessary to commence a chemical reaction by disrupting the bonds of reactant molecules and creating the activated complex or transition state. It signifies the energy threshold that must be surmounted for a reaction to transpire. Activation energy is typically represented as Ea.

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उत्तर २

Activation energy may be defined as the excess energy that the reactant molecules (having energy less than the threshold energy) must acquire in order to cross the energy barrier and to change into the products.

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पाठ 3: Chemical Kinetics - REVIEW EXERCISES [पृष्ठ २५०]

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नूतन Chemistry [English] Class 12 ISC
पाठ 3 Chemical Kinetics
REVIEW EXERCISES | Q 4.70 i. | पृष्ठ २५०
नूतन Chemistry [English] Class 12 ISC
पाठ 3 Chemical Kinetics
REVIEW EXERCISES | Q 4.82 | पृष्ठ २५०
नूतन Chemistry [English] Class 12 ISC
पाठ 3 Chemical Kinetics
REVIEW EXERCISES | Q 4.69 i. | पृष्ठ २५०
नूतन Chemistry [English] Class 12 ISC
पाठ 3 Chemical Kinetics
VERY SHORT ANSWER TYPE QUESTIONS | Q 42. | पृष्ठ २६३

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संबंधित प्रश्‍न

(b) Rate constant ‘k’ of a reaction varies with temperature ‘T’ according to the equation:

`logk=logA-E_a/2.303R(1/T)`

Where Ea is the activation energy. When a graph is plotted for `logk Vs. 1/T` a straight line with a slope of −4250 K is obtained. Calculate ‘Ea’ for the reaction.(R = 8.314 JK−1 mol−1)


The rate constant of a first order reaction increases from 4 × 10−2 to 8 × 10−2 when the temperature changes from 27°C to 37°C. Calculate the energy of activation (Ea). (log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)


What will be the effect of temperature on rate constant?


The activation energy for the reaction \[\ce{2 HI_{(g)} -> H2_{(g)} + I2_{(g)}}\] is 209.5 kJ mol−1 at 581 K. Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy?


The rate constant for the decomposition of N2O5 at various temperatures is given below:

T/°C 0 20 40 60 80
105 × k/s−1 0.0787 1.70 25.7 178 2140

Draw a graph between ln k and `1/T` and calculate the values of A and Ea. Predict the rate constant at 30º and 50ºC.


The rate constant for the decomposition of hydrocarbons is 2.418 × 10−5 s−1 at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of pre-exponential factor?


The decomposition of hydrocarbon follows the equation

k = `(4.5 xx 10^11 s^-1) e^(-28000 K//T)`

Calculate Ea.


In the Arrhenius equation for a first order reaction, the values of ‘A’ of ‘Ea’ are 4 × 1013 sec−1 and 98.6 kJ mol1 respectively. At what temperature will its half life period be 10 minutes?

[R = 8.314 J K1 mol1]


The rate constant of a first order reaction are 0.58 S-1 at 313 K and 0.045 S-1 at 293 K. What is the energy of activation for the reaction?


Calculate activation energy for a reaction of which rate constant becomes four times when temperature changes from 30 °C to 50 °C. (Given R = 8.314 JK−1 mol−1). 


What is the effect of adding a catalyst on Activation energy (Ea)


Explain the following terms :

Half life period of a reaction (t1/2)

 

 

The rate of chemical reaction becomes double for every 10° rise in temperature because of ____________.


Consider figure and mark the correct option.


Which of the following graphs represents exothermic reaction?

(a)  

(b)  

(c)  


During decomposition of an activated complex:

(i) energy is always released

(ii) energy is always absorbed

(iii) energy does not change

(iv) reactants may be formed


Which of the following statements are in accordance with the Arrhenius equation?

(i) Rate of a reaction increases with increase in temperature.

(ii) Rate of a reaction increases with decrease in activation energy.

(iii) Rate constant decreases exponentially with increase in temperature.

(iv) Rate of reaction decreases with decrease in activation energy.


Why in the redox titration of \[\ce{KMnO4}\] vs oxalic acid, we heat oxalic acid solution before starting the titration?


Total number of vibrational degrees of freedom present in CO2 molecule is


The activation energy in a chemical reaction is defined as ______.


The activation energy in a chemical reaction is defined as ______.


Arrhenius equation can be represented graphically as follows:

The (i) intercept and (ii) slope of the graph are:


The decomposition of N2O into N2 and O2 in the presence of gaseous argon follows second-order kinetics, with k = (5.0 × 1011 L mol−1 s−1) `"e"^(-(29000  "K")/"T")`. Arrhenius parameters are ______ kJ mol−1.


An exothermic reaction X → Y has an activation energy 30 kJ mol-1. If energy change ΔE during the reaction is - 20 kJ, then the activation energy for the reverse reaction in kJ is ______.


A schematic plot of ln Keq versus inverse of temperature for a reaction is shown below

The reaction must be:


A first-order reaction is 50% complete in 30 minutes at 300 K and in 10 minutes at 320 K. Calculate activation energy (Ea) for the reaction. [R = 8.314 J K−1 mol−1]

[Given: log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021]


What happens to the rate constant k and activation energy Ea as the temperature of a chemical reaction is increased? Justify.


The rate of a reaction quadruples when temperature changes from 27°C to 57°C calculate the energy of activation. 

(Given: R = 8. 314 J K−1 mol−1, log 4 = 0.6021)


Assertion (A): A reaction can have zero activation energy.

Reason (R): The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to the threshold value is called activation energy.

In the light of the above statements, choose the correct answer from the options given below:


Given below are two statements:

Statement I: The nutrient deficient water bodies lead to eutrophication.

Statement II: Eutrophication leads to decrease in the level of oxygen in the water bodies.

In the light of the above statements, choose the correct answer from the options given below:


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