Sound absorption studies of ternary systems

The peak sound absorption region of ternary systems of water-2-propanolurea, water-2-propanol-tetraethylammonium bromide, water-2-propanol-1,10-bis(triethylammonium)decane dibromide, and the binary system water-2-propanol has been studied at 10, 30, and 50 MHz, and in the temperature range 1.4 to 35°C. The results from the binary system show that the peak sound absorption composition (PSAC) is shifted to higher alcohol composition and (/f²)_max decreases with increasing temperature. At constant frequency, increased urea concentration has the same effect on PSAC and (/f²)_max values as does an increase in temperature for the binary system. All salts decrease /f² values at low concentrations but differ remarkably at higher concentrations. The results are interpreted qualitatively as showing the excess sound absorption in the PSAC region to be intimately related to the structural characteristics of water.