In: Chemistry
A) 2HI(g)H2(g)+I2(g)
rate of reaction=r=-d[HI]/dt=k[HI]^2, k=rate constant
given
r1=-d[HI]/dt=k1[HI]^2=2.35*10^-7 (at 283k)
r2=-d[HI]/dt=k2[HI]^2=1.62*10^-3 (at 427k)
taking ratio,
r1/r2=k1/k2=2.35*10^-7/1.62*10^-3 =1.45*10^-4
A) Arrhenius equation,
lnK=lnA-Ea/RT
so ln(k1/k2)=Ea/R(1/T2-1/T1)
T1=283+273=556K , T2= 427+273=700K T=temperature,Ea=activation energy,R=gas constant
ln(1.45*10^-4)=Ea/8.314J/K mol(1/700-1/556)
-8.873=Ea/8.314J/K mol(0.00143-0.00180)
-8.873=Ea/8.314J/K mol(-0.00037)
Ea=-8.873*8.314J/K mol/(-0.00037)=199378.708 J/mol=199.379 KJ/mol
B)k3=2.91*10^-4
let T=T3 for this reaction
k1/k3=2.35*10^-7/2.91*10^-4=0.807*10^-3
ln(k1/k3)=Ea/R(1/T3-1/T1)
ln(0.807*10^-3)=199378.708 J/mol/8.314J/k mol(1/T3-1/556)
-7.122=23981.081(1/T3-0.00180)
-2.970*10^-4=(1/T3-0.00180)
1/T3=-2.970*10^-4+0.00180=0.00150
T3=666.667K