The activation energy of a certain uncatalysed reaction at 300K is 76 kJ/mol.The activation energy is lowered by 19 kJ/mol by the use of catalyst. By what factor, the rate of catalysed reaction is lowered?

K = Ae^-E/RT                                      (E is activation energy)

rate(R)= K(a)ⁿ                     (k=rate constant & a is concentration  , n is order of reaction)                  

rate directily proportional to rate constant so

R₁/R₂ = K₁/K₂ = e^{[-E₁+E₂]/RT}           

            =e^[-76+19]/RT 

R₁/R₂ = e^-2.28                                       (e = 2.8 approx)

R₂ = 8R₁