www.instituteofscience.com
[D] In search of the elusive hydration number. S.H. Shakman
1.For Na+ & Li+, ratios between Fig.1: Na+ Li+ Ratio
relative hydration nos.(H), in 14 [FLINT** 11 19 .579]
sets of data by 9 investigators MacInnes* 2.0 4.7 .426
in Amis* (average 607.6 are " 8.4 14 .600
generally compatible with ratio " 14.9 23 .648
maximally prescribed by Flint** " 9.8 14.3 .685
(11/19=.579) based on atomic no. Washburn* 8.4 14 .600
[Z] & valence[C] per equation Baborovsky*8-9 13-14 .630
H=23-(Z+C) [see fig.1] " 9 14 .643
2.Degree of persistence of hy- " 44.5 62 .718
drates at elevated temperatures, Collet* 5 7 .714
in general agreement w/relative Haase* 13 22 .591
hydration nos. per Flint**, is Ulich* 2-4 6-7 .462
evidenced by comparing ratios, Devyatykh* 10 21 .476
relative to Na+=1.00, Robinson* 5 7 .714
of observed (CRC'67) to Gapon* 3 5 .600
calculated conductivi- fig.2: (h/a)0øC 18øC 25øC 50øC 75øC
ties, calculated as in- Na+BASE (h)1.00 1.00 1.00 1.00 1.00
verse-sq.-root of anhy- K+ (h)1.01 .97 .95 .91 .89
drous(a) [Wa=2(Z+C)] or C2H3O2- (h) .98 1.00 1.00 1.02 1.04
hydrated(h) [Wh=Wa+18H] Ba++ (a) .92 .91 .92 .92 .93
weights (for 8 ions with La+3 (a) .99 1.03 1.04 1.07 1.10
ratios w/in 10% of BASE SO4-- (a)1.02 1.01 1.00 .98 .98
at 0&C) after Graham C2O4-- (a) .92 .89 .88 .86 .84
per Flint [see fig.2]. OH- (a)1.08 1.06 1.01 .93 .83
*AMIS,E.& J.HINTON,Solvent Effects...(1973) Tables 3-1,4,15.
**FLINT,LH,J.Wash.Acad.Sci.22(1932)97+;-Behavior...(1964)21.
Fig.2. example: calculation for K+=.97 at 18&C: Observed conductivities for K+ and Na+ are 64.6 & 43.5 resp.; anhydrous weights[(Wa)=2(Z+C)] 40 & 24, hydrated weights [(Wh)= Wa+18H] 94 & 222, and calculated conductivities 1//94=.1031 & 1//222= .0671 resp.; (64.6/.1031)/(43.4/.06712)=.97.
BOOKS
InstituteOfScience.com
Copyright 1985
Txu219626; 1986Txu242823 S H
Shakman All rights reserved.