Sonochemistry and solution chemistry have been explicitly brought together by analysing the effect of ultrasound on kinetics of ester hydrolysis and benzoin condensation, measured by the authors, and similar kinetic data for the solvolysis of tert-butyl chloride, compiled from literature. For the first time the power ultrasound, reaction kinetics and linear free-energy relationships were simultaneously exploited to study ionic reactions in water and aqueous-organic binary solvents and the importance of hydrophobic ground-state stabilisation of reagents in aqueous solutions was discussed. This book presents and discusses this approach, which has opened novel perspectives for wider understanding of the effect of sonication on chemical reactions in solution, as well as on solvation phenomena in general.