A technique and a method for the continuous, simultaneous, and automatic measurement of density and speed of sound in pure liquids and solutions

A highly accurate experimental technique is presented for the continuous, simultaneous, and automatic determination of speed of sound and density in pure liquids and solutions. The digital elements of the equipment are fully computerized by a PC, via IEEE-488 bus and RS232C serial port interfaces. The software, a LabView program developed by us, controls the automatic measuring procedure and obtains, for each concentration, the speed of sound from an average over 150 measurements of the time between two consecutive echoes of a signal digitized at 1 G S/s with 250 000 points, and the density from an average over 90 000 measurements of the period of oscillation of a vibrating tube. The experimental technique and the software have been setup by measuring, at 298.15 K, the speed of sound and density of aqueous solutions of procaine hydrochloride, p-nitrophenyl-α-D-glucopyranoside, and β-cyclodextrin, previously measured by us with a manual method. A comparison between both methods is also included.