Editing Ultrasound (section)

===Sonochemistry===
{{Main|Sonochemistry}}
Power ultrasound in the 20–100&nbsp;kHz range is used in chemistry. The ultrasound does not interact directly with [[molecule]]s to induce the chemical change, as its typical wavelength (in the millimeter range) is too long compared to the molecules. Instead, the energy causes [[cavitation]] which generates extremes of temperature and pressure in the liquid where the reaction happens. Ultrasound also breaks up solids and removes [[Passivation (chemistry)|passivating]] layers of [[Chemically inert|inert]] material to give a larger [[surface area]] for the reaction to occur over. Both of these effects make the reaction faster. In 2008, [[Atul Kumar (chemist)|Atul Kumar]] reported synthesis of Hantzsch esters and polyhydroquinoline derivatives via multi-component reaction protocol in aqueous [[micelles]] using ultrasound.<ref>{{cite journal |last1=Kumar |first1=Atul |last2=Maurya |first2=Ram |title=Efficient Synthesis of Hantzsch Esters and Polyhydroquinoline Derivatives in Aqueous Micelles |journal=Synlett |date=April 2008 |volume=2008 |issue=6 |pages=883–885 |doi=10.1055/s-2008-1042908 }}</ref>

Ultrasound is used in [[Liquid-liquid extraction|extraction]], using different frequencies.