Kinetic Analysis of the Redox Reaction in an Aqueous Vanadium-Oxalate System

The redox reaction between dioxovanadium(V) and oxalate is proposed as a suitable system to analyze the kinetics of a twostep reaction mechanism using UV-vis spectroscopy. First, the spectra of dioxovanadium(V) and its reduced counterpart oxovanadium(IV) are compared and explained using the crystal field theory. The change in absorbance can be used to determine the reaction order and rate equation by the method of initial rates. Next, the students are introduced to the Guggenheim time-lag method to calculate the apparent rate constant. By performing the experiment at different temperatures, ranging from 20 to 50 °C, an Arrhenius plot can be constructed to obtain the activation energy for this redox reaction.