Advertisements
Advertisements
Question
A first-order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction. (Given : log 2 = 0·3010, log 4 = 0·6021, R = 8·314 JK–1 mol–1)
Advertisements
Solution
Given
t1/2 = 40 min at temperature (T1) = 300 K
t1/2 = 20 min at temperature (T2) = 320 K
t1/2 = 40 min, t1/2 = 20 min
`k_1 = 0.693/40`
`k_2 = 0.693/20`
According to Arrhenius equation
`log (k_2/k_1) = "E"_"a"/(2.303 " R") [1/"T"_1 - 1/"T"_2]`
`= "E"_"a"/(2.303 " R") [("T"_2 - "T"_1)/("T"_1"T"_2)]`
`log ((0.0693/20)/(0.0693/40)) = "E"_"a"/(2.303 xx 8.314) [(320 - 300)/(300 xx 320)]`
`therefore 0.3010 = "E"_"a"/19.147 [0.0002083]`
Ea = 27664 J/mol
Ea = 27.7 kJ/mol
APPEARS IN
RELATED QUESTIONS
The rate constant of a first order reaction increases from 4 × 10−2 to 8 × 10−2 when the temperature changes from 27°C to 37°C. Calculate the energy of activation (Ea). (log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)
The rate of the chemical reaction doubles for an increase of 10 K in absolute temperature from 298 K. Calculate Ea.
The decomposition of hydrocarbon follows the equation
k = `(4.5 xx 10^11 s^-1) e^(-28000 K//T)`
Calculate Ea.
Define activation energy.
What is the effect of adding a catalyst on Activation energy (Ea)
During decomposition of an activated complex:
(i) energy is always released
(ii) energy is always absorbed
(iii) energy does not change
(iv) reactants may be formed
Which of the following statements are in accordance with the Arrhenius equation?
(i) Rate of a reaction increases with increase in temperature.
(ii) Rate of a reaction increases with decrease in activation energy.
(iii) Rate constant decreases exponentially with increase in temperature.
(iv) Rate of reaction decreases with decrease in activation energy.
Why does the rate of a reaction increase with rise in temperature?
The equation k = `(6.5 xx 10^12 "s"^(-1))"e"^(- 26000 " K"//"T")` is followed for the decomposition of compound A. The activation energy for the reaction is ______ kJ mol-1. (Nearest integer) (Given: R = 8.314 JK-1 mol-1)
A schematic plot of ln Keq versus inverse of temperature for a reaction is shown below
The reaction must be:
