Volumetric properties of aqueous 1-1 electrolytes near and above the critical temperature of water III. Experimental densities and apparent molar volumes of CsBr(aq) to the temperature 725.5 K and the pressure 38.0 MPa, comparison with other 1-1 electrolytes, and extrapolations to infinite dilution for NaCl(aq)
✍ Scribed by Vladimir Majer; Robert H. Wood
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 704 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0021-9614
No coin nor oath required. For personal study only.
✦ Synopsis
A vibrating-tube densitometer was used for measuring differences in densities between (\operatorname{Cs} \mathrm{Br}(\mathrm{aq})) and water from molalities of (0.0024 \mathrm{~mol} \cdot \mathrm{kg}^{-1}) to (0.50 \mathrm{~mol} \cdot \mathrm{kg}^{-1}), at temperatures between (604.4 \mathrm{~K}) and (725.5 \mathrm{~K}), and at pressures from (18.4 \mathrm{MPa}) to (38.0 \mathrm{MPa}). The temperature and molality dependences of the derived apparent molar volumes are compared with those for the other 1-1 electrolytes. Anomalous bchavior was observed for dilute solutions in the region of low density of water (\left(\rho_{0}<350 \mathrm{~kg} \cdot \mathrm{m}^{-3}\right)) where the salts with the lowest ionic radii had the least negative values of the apparent molar volumes. This behavior indicates that the ion pairs with the smallest distance of closest approach have the least negative apparent molar volumes. Using the Pitzer parametric equation and a simplified model describing ion-pairing in dilute solution, the partial molar volumes at infinite dilution were estimated when the density of water was greater than (280 \mathrm{~kg} \cdot \mathrm{m}^{-3}). Under these conditions, there was no evidence that critical-point phenomena invalidated the estimate.