On the quantitative measure of a sonochemical effect in heterogeneous sonochemistry

The measurement of a sonochemical effect (SE) requires the definition of th e reference conditions for the so-called "silent reaction". It is shown tha t it is impossible to define SE correctly in the case of heterogeneous reac tions, due to the dramatic effect of the agitation on reaction rates, This is true not only from the quantitative point of view (effect of ultrasound on reaction rates) but also from the qualitative perspective (change of rea ction pathway when ultrasound is applied). The first, and most dramatic, ex ample of chemical switching described in the literature, and claimed to be due to ultrasound, is proven also to be observable under efficient agitatio n conditions.