A treatise on the theory of solution including the phenomena of electrolysis . We have now toexamine in greater detail the quantitative relations, and to CH. IV] SOLUBILITY 79 give some further account of the experimental determinationswhich have been made on the subject. In a saturated solution there is equilibrium between thesolid and the solution, and any structural change in either of thetwo will produce a change in the equilibrium. Thus, as we ex-plained on p. 53, the change in the nature of the solid crystalsof hydrated sodium sulphate, Na2S04. 10 H2O, which are trans-formed into the anh
A treatise on the theory of solution including the phenomena of electrolysis . We have now toexamine in greater detail the quantitative relations, and to CH. IV] SOLUBILITY 79 give some further account of the experimental determinationswhich have been made on the subject. In a saturated solution there is equilibrium between thesolid and the solution, and any structural change in either of thetwo will produce a change in the equilibrium. Thus, as we ex-plained on p. 53, the change in the nature of the solid crystalsof hydrated sodium sulphate, Na2S04. 10 H2O, which are trans-formed into the anhydrous salt Na^SOj at a temperature of 32°G,causes a sudden change of direction in the solubility curve(Fig. 32). The transition point is the temperature at whichthe non-variant system salt-hydrate-solution-vapour can exist inequilibrium ; below this temperature the solubility of sodiumsulphate increases with rising temperature, above it the solu-bility diminishes. This change was formerly explained by thesupposition that below 32°6 hydrated salt is present in solution,. Fig. 32. and above that temperature the liquid contains the anhydroussubstance. Our present knowledge of the general problem ofequilibrium shows at once that such a supposition is un-necessary ; moreover, there is evidence of a direct nature whichproves it to be untenable. If this view were correct, we shouldexpect the physical properties of the solution to differ fromeach other above and below the transition point, but in none ofthose properties has a sudden change been found.^ Ostwalds Lehrhuch, or Solutions, p. 74. 80 SOLUTION AND ELECTROLYSIS [CH. IV A similar continuity of properties holds good at the pointof saturation. None of the curves indicating the Supersaturation. . ~ i • i variation with concentration or any physical pro-perty of the solution exhibit a sudden change of curvature asthe saturation point is passed and a supersaturated solutionobtained. This has been shown for the freezing points b
Size: 1621px × 1542px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishercambr, bookyear1902
