Redox- Reaction Of Pyridine, 2, Carboxylic Acid Hydrazide By Ammonium Metavanadate, A Kinetics And Mechanistic Approach
Abstract
Redox-reaction of Pyridine, 2, carboxylic acid hydrazide by ammonium metavanadate for chemical kinetics and mechanistic determination was carried out under pseudo first order condition. The complex formed between the reactants gives picolinic acid, on its decomposition where Single electron transfer was observed during the course of this redox- reaction with intervention of free radical. The effect of different initial Concentration of reactants on the reaction rate was studied. The pseudo-first order kinetic behavior of the reaction is due to constancy in specific reaction rates at various amount of ammonium metavanadate.Increase in concentration of Pyridine, 2, carboxylic acid shows decreases in the specific rate of the reaction. The rate of reaction is directly proportional to the amount of the acid as well as dielectric constant of the medium of the reaction. There is no effect of change in concentration of salt as well as various salts of the same concentration under the experimental conditions on the specific rate of the reaction. The variation of ionic strength during reacton has negligible effect on specific rates of reacton. The temperature effect on rate of the reaction was studied from 30oC to 55oC and the rates of the reaction are found to be directly proportional to the increase in temperature of the reaction. The values of thermodynamic activation parameters support the mechanism proposed which is further supported by considerable decrease in entropy of activation.(-?S # = -141.65, J K-1 mol-1).The investigation of the mechanism of the reaction was done by measuring the absorbance of the ammonium metavanadate at 390 nm.
