Speeds of sound and isentropic compressibilities of diethylene glycol dimethyl ether - n-Alcohol mixtures at 298.15 K

The speeds of sound has been obtained at a frequency of 4 MHz in diethylene glycol dimethyl ether + methanol, + ethanol, + 1-butanol, and + 1-pentanol across the entire composition range, at the temperature 298.15 K and atmos pheric pressure using a NUSONIC velocimeter based on the sing-around techni que. The ultrasonic speed values have been combined with those of the exces s molar volumes converted to densities to obtain estimates of the product K -S,K-m of the molar volumes and isentropic compressibility kappa (S), and e xcess quantity K-S,m(E). The K-S,m(E) values are negative over the entire r ange of composition for all mixtures with the exception of 1-pentanol, whic h changes sign from positive to negative. The magnitude of K-S,m(E) increas e with the number of carbon atoms in the n-alcohol. The deviations of the s peeds of sound u(D) from their ideal values u(id) in an ideal mixture were also calculated for all measured mole fractions. The behaviour of u, u(D), and K-S,m(E) with composition and the number of carbon atoms in the alcohol molecule is discussed.