Estimation of kinetic parameters and activation energy of ester by spectrophotometric method

To estimate the kinetic parameters, activation energy and half life time of the hydrolysis of ester with hydrochloric acid monitored by spectrophotometric method. The first order fits were automatically drawn and the values of the first order rate constants (k) were calculated using standard equations as part of the program. Rate of reaction is the change in the number of molecules of reacting species per unit volume per unit time. A simple sensitive kinetic spectrophotometric method presented for the determination of rate constant, order of reaction, activation energy and half life time. This method based on a kinetic investigation of methyl acetate and hydrochloric acid at 35°C and 45°C temperature. The reaction followed spectrophotometrically by measuring the absorbance at 500 nm as a function of time. The initial rate and fixed time methods utilized for construction of calibration graphs successfully for the determination of rate constant, order of reaction, activation energy and half life time. The rate constant after calculation from the graphs was approximately k1 ≈ 0.242 min-1 k2 ≈ 0.253min-1 by titration and spectrophotometric method respectively, order of reaction found to be first order, activation energy for this reaction is 3.86995 x 10-8 kJ/mol and half life time t1 ≈ 2.864 min t2 ≈ 2.736 min. One factor that influences the absorbance of a sample is the concentration. As the concentration increases, more radiation is absorbed by the sample and the absorbance increase. Therefore, the absorbance is directly proportional to the concentration.