Mystery of discrepancies in speed of sound in water cleared up by study of ions

Although the speed of sound in a range of electrolytes has been well studied since the 1950s, only the overall effect of these ions in a solution has ever been measured. Now Theo van de Ven and Yiwei Jiang have quantified the speed of sound in aqueous solutions for specific ions and discovered that anions decrease the speed of sound – as expected – while surprisingly cations actually speed it up.

Van de Ven says that ‘it was a bit surprising’ that no one had apparently ever looked into this before. He adds that having a better understanding of the effects of different components in a solution on the speed of sound could be a valuable tool for analysing the composition of complex solutions.