Correct Answer - a. Ea=239.339kJmol-1
b.T=669K
a. According to Arrhenius equation, k=Ae-Ea/RT
logk=logA-
Ea
2.303RT
......(i)
Comparing with the griven equation
logk=14.34-1.25×104K/T...(ii)
∴
Ea
2.303RT
=
1.25×104K
T
orEa=2.303R×1.25×104K
=2.303×(8.314JK-1mol-1)×1.25×104K
=239.34kJmol-1
b. When t1/2=256min,k=
0.693
t1/2min
=
0.693
256×60s
=4.51×10-5s-1
Substitute the value of k in Eq.(ii),
log(4.51×10-5s-1)=14.34-
1.25×104K
T
log(-5+0.6542)=14.34-
1.25×104K
T
or
1.25×104K
T
=18.6858
orT=669K