Chemical Kinetics - Result Question 11

####12. If a reaction follows the Arrhenius equation, the plot lnkvs 1/(RT) gives straight line with a gradient (y) unit. The energy required to activate the reactant is

(2019 Main, 11 Jan I)

(a) yR unit

(b) y unit

(c) yR unit

(d) y unit

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Answer:

Correct Answer: 12. (a)

Solution:

  1. The temperature dependence of rate of a chemical reaction is expressed by Arrhenius equation as, k=AeEα/RT

where, A= Arrhenius factor or frequency factor or pre-exponential factor

R= Gas constant,Ea= Activation energy Taking log on both sides of the Eq. (i), the equation becomes lnk=lnAEaRT

On comparing with equation of straight line (y=mx+c), the nature of the plot of lnkvs1RT will be:

(i) Intercept =C=lnA

(ii) Slope/gradient =m=Ea=yEa=y

So, the energy required to activate the reactant, (activation energy of the reaction, Ea is = y )



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