The temperature dependent redox decomposition rate constants of ascorbic acid (AsAc) in aqueous solutions were quantified in the presence of ammonium iron(III) sulfate dodecahydrate (Fe-cat) and tert-butylhydroperoxide (TBHP). Decomposition rates were determined in a temperature range from 35-75 degrees C with respect to the component ratios. First-order kinetics were observed up to specific conversions (similar to 20-80%) for AsAc decomposition. The application of a flexible Weibull model provided a good and comparable description (R-2 >= 0.992) of decomposition processes up to high AsAc conversions (96%) at all studied reaction conditions. The activation energy was determined as a function of AsAc and Fe-cat ratios (38-79 kJ mol(-1)). Statistical modeling facilitated the prediction of rate constants. Thus, it was possible to adjust the reaction rate of emulsion copolymerizations of vinyl acetate and Versa10 in a broad temperature range (10-70 degrees C) by variation of the Fe-cat content.