मराठी
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]

APPEARS IN

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

व्हिडिओ ट्यूटोरियलVIEW ALL [1]

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)


 

Consider the reaction

`3I_((aq))^-) +S_2O_8^(2-)->I_(3(aq))^-) + 2S_2O_4^(2-)`

At particular time t, `(d[SO_4^(2-)])/dt=2.2xx10^(-2)"M/s"`

What are the values of the following at the same time?

a. `-(d[I^-])/dt`

b. `-(d[S_2O_8^(2-)])/dt`

c. `-(d[I_3^-])/dt`

 

 

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?


Consider a certain reaction \[\ce{A -> Products}\] with k = 2.0 × 10−2 s−1. Calculate the concentration of A remaining after 100 s if the initial concentration of A is 1.0 mol L−1.


The rate of a reaction quadruples when the temperature changes from 293 K to 313 K. Calculate the energy of activation of the reaction assuming that it does not change with temperature.


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). 


A first-order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction. (Given : log 2 = 0·3010, log 4 = 0·6021, R = 8·314 JK–1 mol–1)


 Write a condition under which a bimolecular reaction is kinetically first order. Give an example of  such a reaction. (Given : log2 = 0.3010,log 3 = 0.4771, log5 = 0.6990).


 Predict the main product of the following reactions:


The chemical reaction in which reactants require high amount of activation energy are generally ____________.


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


Consider figure and mark the correct option.


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


The reaction between \[\ce{H2(g)}\] and \[\ce{O2(g)}\] is highly feasible yet allowing the gases to stand at room temperature in the same vessel does not lead to the formation of water. Explain.


Oxygen is available in plenty in air yet fuels do not burn by themselves at room temperature. Explain.


For an endothermic reaction energy of activation is Ea and enthalpy of reaction ΔH (both of there in KJ moI–1) minimum value of Ea will be ______.


The slope of Arrhenius Plot `("In"  "k"  "v"//"s" 1/"T")` of first-order reaction is −5 × 103 K. The value of Ea of the reaction is. Choose the correct option for your answer. [Given R = 8.314 JK−1mol−1]


Arrhenius equation can be represented graphically as follows:

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


Explain how and why will the rate of reaction for a given reaction be affected when the temperature at which the reaction was taking place is decreased.


The activation energy of one of the reactions in a biochemical process is 532611 J mol–1. When the temperature falls from 310 K to 300 K, the change in rate constant observed is k300 = x × 10–3 k310. The value of x is ______.

[Given: ln 10 = 2.3, R = 8.3 J K–1 mol–1]


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.


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

The reaction must be:


It is generally observed that the rate of a chemical reaction becomes double with every 10°C rise in temperature. If the generalisation holds true for a reaction in the temperature range of 298 K to 308 K, what would be the value of activation energy (Ea) for the reaction?


Activation energy of any chemical reactions can be calculated if one knows the value of:


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)


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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