Q.

Consider the following plots of log of rate constant k (log k) vs 1/T for three different reactions.  The correct order of activation energies of these reactions is  [2025]

1 Ea2>Ea1>Ea3  
2 Ea1>Ea3>Ea2  
3 Ea1>Ea2>Ea3  
4 Ea3>Ea2>Ea1  

Ans.

(1)

k=Ae-Ea/RT 

lnk=lnA+lne-Ea/RT 

lnk=lnA-EaRT 

logk=logA-Ea2.303R(1T)

Slope of log k vs 1T graph is -Ea2.303R 

Thus more negative slope means more activation energy.