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Specific Gravity of Aqueous Solutions. S.H. Shakman
Specific gravity (S.G.) for a number of solutes may be approximated using the equation: S.G.= ((1000+ [g/l / (1+ Waz/ Whz)])) /1000, as derived from Flint*; when g/l= grams/liter anhydrous solute; Waz is the sum of anhydrous ionic weights (Wa), each equal to: 2(atomic no. +/- valence); Whz is the sum of hydrated ionic weights (Wh), each equal to: Wa+18H, when H (hydration no.) = 23n - (atomic no. +/- valence), with H varying from 23 to 0 and n from 1 to 4. For example, UO2(NO3)2 is assumed to consist of U+6((Wa=196, Wh=196 [H = 23(4) - (92+6), thus U+6 does not hydrate])); 2 O--(Wa=12, Wh=318); and 2 NO3-(Wa=60, Wh=348). Thus Waz=340, Whz=1528, Waz/Whz=.2225, and calculated S.G. at 2% solute = (1000+ 20.34/1.2225) /1000 = 1.017. Table below lists, for solutions of "A%" (2-20%) solute, observed and calculated specific gravities and error (obs./calc. - 1) for UO2(NO3)2; and error values only for 4 other solutes. Table - Specific Gravity of Aqueous Solutions
A% UO2(NO3)2 MgI2 CdCl2 CaCl2 CoCl2 CdI2 CsBr Obs.** g/l Calc. Error = (Observed**/Calculated - 1) 2 1.017 20.34 1.017 .0000 -.0015 -.0019 -.0010 -.0008 -.0010 -.0016 4 1.036 41.44 1.034 .0019 -.0013 -.0015 -.0005 -.0002 -.0004 -.0015 8 1.072 85.76 1.070 .0019 -.0012 -.0010 -.0004 .0007 .0003 -.0014 12 1.110 133.20 1.109 .0009 -.0010 .0007 -.0013 .0012 .0006 -.0015 16 1.149 183.84 1.150 -.0009 -.0009 .0012 -.0026 .0013 .0010 -.0016 20 1.194 238.80 1.195 -.0008 -.0010 .0014 -.0048 .0005 .0015 -.0018 *FLINT, L.H., Behavior Patterns of Hydration (1964), 21, 30. **LANGE'S Handbook of Chemistry, 10th Ed. (1967), 1169-82.
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