Partial molar volumes and partial molal adiabatic compressibilities of nitroamminecobalt(III) complexes in water at 25.degree.C

Abstract

Densities and ultrasonic propagating velocities of aqueous solutions of a series of nitroamminecobalt(III) complexes have been measured at 25 "C at concentrations less than 0.1 mol kg-l. Partial molar volumes, v2", have been determined by extrapolation of the relationship between 4, -Svm1f2 and m, where S, is the coefficient given by the Debye-Huckel (DH) theory. In this relationship, nearly horizontal slopes have been observed for all samples. Infinite-dilution values of partial molal compressibility, have been evaluated from the linear extrapolation of the empirical plot of 4b against "I2. The concentration dependence of 4b of these complexes is much higher than those observed for ordinary electrolytes of the same valency type. Values of vzo and 4bo assigned to the complex ions [Co(N02),,(NH3),,13-" increase regularly with the number of the ligand NO2-contained in the complex. Analysis of the observed variation of v2" and $bo of complex ions has shown that even for nonelectrolytic complex [CO(NO,)~(NH,),]~ electrostriction should occur in solution. Introduction About 15 years ago, using an ultrasonic interferometer and Ostwald-type pycnometer, we1v2 determined the compressibilities of aqueous solutions of such cobalt complexes as [CO(NH,),& (X = Cl-, Br-, or NO<), [Co(en),]C1, (en = ethylenediamine), and [ C~( d i e n )~] C l~ (dien = diethylenetriamine), etc., and calculated the hydration number of these complex salts. Recent development of

Generation and observation of GHz ultrasonic waves on liquid surfaces and a liquid/liquid interface by transient reflecting grating method

“…[12][13][14] Furthermore, the hydration number of ions in an electrolyte solution has been determined from the adiabatic compressibility obtained by measuring sound velocity in the solution. [15][16][17] Thus, we focus on the application of this method to liquid surfaces and liquid/liquid interfaces. Therefore, techniques to induce and observe ultrasonic waves on liquid surfaces and liquid/liquid interfaces with the frequency from the MHz to GHz region are highly desirable.…”

Partial molar volumes for inorganic complexes

“…Co(NH 3 ) 5 Cl 2þ -are usually more appropriate for study of inner-sphere electron transfer and substitution processes. Table 3 [30,45,46] forms a link between this and the previous section, showing how partial molar volumes vary with successive ligand replacements as one binary complex undergoes stepwise change to another. Secondly, it shows how the choice of single-ion reference assumption affects partial molar volumes.…”

“…All the partial molar volume values for anions are positive; however, the very small values for fluoride and carbonate suggest that solvation of these hydrophilic species is almost balancing the intrinsic size contribution to the overall partial molar volume. Table 2 [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] lists values for the partial molar volumes of a range of binary (homoleptic) complexes ML nAE 6 and MðLLÞ nAE 3 , where L and LL are mono-and bidentate ligands, respectively. The partial molar volume of CrðNH 3 Þ 3þ 6 is larger than that of CrðOH 2 Þ 3þ 6 (V i ¼ 57.0 cm 3 mol À1 ) [27], in contrast to À53.0 cm 3 mol À1 for Cr 3þ ( similarly has a larger value (127 cm 3 mol À1 [27,29] than CoðenÞ 3þ 3 , whose recommended value (V i ¼ 121 cm 3 mol À1 ) is based on data in references [25,27,29,38] [38,40,41], although the value reported for Znð phenÞ 2þ 3 is, unexpectedly, not smaller than that for Cuð phenÞ 2þ 3 [40].…”

Partial molar volumes and compressibilities of 1-1 type chlorides, bromides, tetraphenylphosphonium chloride, and sodium tetraphenylborate in water-acetone mixtures

“…Procedure of Measurements. In our previous reports (2)(3)(4) the ultrasonic velocities were measured for a series of complex compounds by using a laboratory constructed slng-around apparatus. The slng-around method Is suitable to detect the small variation of ultrasonic velocity of the sample solution from that of certain reference liquid.…”