Question

The rate of reaction `((dx)/(dt))` varies with nature, physical state and concentration of reactants, temperature, exposure to light and catalyst, whereas rate constant `(K)` varies with temperature and catalyst only. The rate constant `K` is given as `K=Ae^(-E_(a)//RT)` where `A` is Arrhenius parameter or pre-exponential factor and `E_(a)` is energy of activation. The minimum energy required for a reaction is called threshold energy and the additional energy required by reactant molecules to attain threshold energy level is called energy of activation.
For a reaction, `Ararr B`, if
`log_(10) K (sec^(-1)) =14-(1.25xx10^(4))/(T)K`, the Arrhenius parameter and energy of activation for the reaction are:
A. (a) `10^(14) sec^(-1), 239.34 kJ`
B. (b) `14, 57.6 kcal`
C. (c ) `10^(14) sec^(-1), 23.93 kJ`
D. (d) `10^(14) sec, 5.76 kcal`

Answer 1

Correct Answer - a
`2.303 log_(10) K=2.303log_(10) A=E_(a)/(RT)`
`:. E_(a)/(2.303R)=1.25xx10^(4)`
`:. E_(a)=1.25xx10^(4)xx2.303xx8.314`
`=239.34xx10^(3) J`
`log A=14 :. A=1xx10^(14)`