QUANTITATIVE SONOCHEMISTRY

The measurement of a sonochemical effect requires a comparison of the reaction rates with and without ultrasound when all other parameters r emain constant. Various artefacts make this last condition difficult t o fulfil. Some of them are discussed in the case of the Diels-Alder re action. To evidence a frequency effect in sonochemistry, the reaction rates have to be compared by changing the frequency alone and maintain ing all the other parameters constant. The major difficulty in fulfill ing this condition led us to use a relative method where a couple of r eactions were studied at 20 kHz and 1.7 MHz. The third topic concerns the effect of ultrasound on various electrochemical reactions for the purpose of producing nano- to microparticles of metals, oxides and sem iconductors.