No abstract

No abstract

No abstract

D ISSOLVED salts generally change the specific gravity of water in direct proportion to their concentration. The magnitude of change, however, depends on the nature and amount of the various dissolved salts. Determination of specific gravity and total dissolved salts (TDS) in a number of surface and subsurface water samples with a high TDS indicated a loose relationship between these two parameters. An empirical formula for calculation of TDS is percentage T DS = (Sp gr -l)j, where j is a common factor.A study of dilute solutions of different salts present in natural waters revealed that there cannot be a common factor, j, for all types of ground waters.An application of the above formula to mixtures of solutions of different salts, however, showed that there can be a common factor for waters of similar hydrochemical facies.Dissolved salts increase the coefficient of expansion of water, lower the temperature of maximum density, decrease association, and increase specific gravity-all in approximately direct proportion to the amount of salt. The Various FormulasThorough investigation of the effect of pure salts on water density has resulted in several explanatory formulas.Val son 1 assigned to cations and anions characteristic numbers which he called moduli.He then obtained the density of a normal solution of salt by adding the moduli to the density of a normal solution of ammonium chloride, which has the lowest density ( 1.015) of all the salts investigated. Bender 2 extended this relationship to other concentrations.Gaehr 3 gave the approx imate relationship between density, d and concentration, c, as log d = me, where m is constant. The relation was valid in only 15 per cent of the cases he investigated.Drude and N ems 4 showed the effect of charged ions on the volume of solvent. They explained the effect of change in volume (electrostriction) on dilution as the consequence of increased ionization.Masson 5 gave the relation between apparent (fictive) molar volume, (V2), and concentration c,as (V2) = °(V2) + aye, where °(V2) is a constant, and (V2) = V -Vo. V 0 and V are the volumes of solvent and solution containing 1 mol of electrolyte. Assuming the change in volume is due only to the electrolyte, then <1>( V2) = M Ido -(l,OOOlao) [ (d -do) IN], where M is the equivalent of the salt, N is the number of equivalents per liter and do and dare the densities of pure water and solution respectively. The Mason equation gen-733

No abstract