The Arrhenius equation is
log10 k2k1 = Ea(R×2.303) ×(T2−T1)(T1 T2)
Given:k2k1=3:R=8.314 JK−1mol−1;T1=20+273=293 K
and T2=50+273=323 K
Substituting the given values in the Arrhenius equation,
log10 3=Ea(8.314×2.303)× (323−293)(323×293)
Ea=(2.303×8.314×323×293×0.477)30
=28811.8 J mol−1
=28.81 k J mol−1
=29 k J mol−1