Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is © the Owner Societies 2015
1 Supplementary Information - A Study of the Relationship between Water and Anions of the 2 Hofmeister Series Using Pressure Perturbation Calorimetry
3 Jordan W. Bye and Robert J. Falconer*
4 Department of Chemical & Biological Engineering, ChELSI Institute, University of Sheffield, Sheffield, 5 S1 3JD, England
6 * To whom the correspondence should be addressed. Telephone +44 114 2228253, Fax +44 114 7 2227501 Email [email protected]
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9 The calculated values for the coefficient of thermal expansion determined using the equation 10 derived in Lin et. al. 2002 using the conventional apparent partial volume (푉̅ ) values from Millero 11 19712 and experimental results for 100 mM salt solutions are shown in Figures S1. The coefficient of 12 thermal expansion for sodium chloride, sodium bromide, sodium iodide, sodium thiocyanide and 13 sodium perchlorate are simplar but the two sodium salts with high charge density anions sodium 14 fluoride and disodium sulphate have markedly different calculated coefficients of thermal 15 expansion. For the two high charge density salts sodium flouride and disodium sulphate, the ̅ 16 conventional apparent partial volume (푉) values differ significantly from the intrinsic volumes (Vint), 17 as shown in Figure S2. It was the observation that the coefficient of thermal expansion calculated for 18 high charge density anions was problematic that led the authors to develop the alternative 19 mathetical approach where the hydration layer was treated as a discrete population of water with 20 an average volume and coefficient of thermal expansion. This idea is supported by a range of 21 analytical methodologies that suggest that water in the first and second layer around an ion is
22 significantly different to pure or bulk water, see the main paper.
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24 Figure S1: Apparent thermal expansion coefficient for a pressure increase (1 to 5 bar) from 7 oC – 92 25 oC for 100 mM disodium sulphate (), sodium fluoride (), sodium chloride (), sodium bromide 26 (|), sodium iodide (), sodium thiocyanate (–) and sodium perchlorate (). The sample size was 300 2 27 μL. Using PPC data and conventional apparent partial volume (V0) (from Millero 1971)
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2 32 Figure S2: The conventional apparent partial volume (V0) (from Millero 1971) versus intrinsic volume 3 33 (Vint) calculated from the ionic radii (from Marcus 1997) of disodium sulphate (), sodium chloride 34 (), sodium bromide (|), sodium iodide () and sodium perchlorate ().
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36 References
37 1. L. N. Lin, J. F. Brandts, J. M. Brandts, V. Plotnikov, Anal. Biochem.2002, 302, 144-60. 38 2. F. J. Millero, Chem. Rev. 1971, 71, 147−176. 39 3. Y. Marcus, Ions Properties, CRC Press, Boca Raton, 1997.