[COSTRIRUTION
S O . 1086 F R O M THE I ) E P A R T M E N T O F C H E M I S T R Y , Y A L E L . N I V E R S I T Y ]
The High Field Conductance of Magnesium Sulfate Relative to Potassium Chloride from 5 to 55"' BY FREDERICK EUGENE BAILEY,J R . ,
.IND
.INDREW PATTERSOK, JR.
RECEIVED MARCH24, 1963 The high field conductance of magnesium sulfate relative to potassiuni chloride in aqueous solution in the concentration range 10-&molar has been determined from 5 to 55' using the differential pulse transformer bridge circuit. The high field conductance when given as Ah& is shown not to be a significantly varying function of temperature, in accordance with t h e predictions of the Onsager-\\'ilsoii theory, but the results arc shoivn to deviate consistently from thc values computed with aid of this theory.
Although a quarter of a century has passed sincc Wien? announced his discovery that the conductances of electrolytic solutions do not conform to Ohm's law under the influence of high potential gradients, only one set of precise data has been presented for a symmetrical valence type strong electrolyte3 with which it is possible to test the ' ~ Wien's theory of Onsager and W i l s ~ n . ~ In papers the temperature was unspecified. The present paper includes data on the high field conductance of magnesium sulfate in aqueous solution, approximately low4molar, relative to potassium chloride over the temperature range 5 to 35'. Experimental The experimental procedure was identical with that ul Gledhill and Pattersori,6 employing a differential pulse transformer bridge circuit. All meitsurements were made with four-microsecond pulse duration. The salts employed were of highest quality reagent grade, purified by recry\tallization. T h e solutions on which conductance ineasurements were actually made were prepared by weight dilution of suitable strong stock solutions of each salt. The strong stock solutions were analyzed by weighing suitable quantities into platinum dishes, evaporating the water, and reweighing. T h e details of t h e procedure are described by Gledhill and Patterson.6 The temperature control was to withiii 0.015 a t 2,5" and within 0.02' a t all other temperatures. All temperatures were measured against ;I recciit 1)' rahI m i teti platinum resistance thermometer.
Results Table I contains the experimental results as well as relative !&Yeti effects computed from the Onsager-\f'ilsoii using the equation
The symbols are those of Harned and Owen.b ' [ h e firs( column lists the field strengths employed, the next two coliimns contain the experimental data, a n d the r ~ m a i n i n g (>olumns are for the theoretical calculations. 'I'hc experimental data are given in the foriri of resist;tric.r ;it low firltl. which is equivalent to zero field for these electrolyte of resistaiices of the magnesium d f a t e ~olritioii;it iiicifield. T h e results are reportcd a i 1 X ; X n . in per writ. l'hv cornputations have been inade in the same \ray ac: in reference 6. The Onsager-U'ilson theory calculatioiis are giveti in essentially the same form, a s equivalent cotiductarice ;it (1) This material is taken from a dissertation submitted b y 1'. 1;. Bailey, Jr., t o the Faculty of the Graduate Schuol of Yale University i n partial fulfillment of the requirements for t h e degree of Doctor of Philosophy, May, 1952. (2) M. Wien and J. hlalsch, Ann. Physik, 83,305 (1927). (3) M. Wien, ibid., 85, 795 (1928); Physik. Z.,29, 761 (19288). (4) W. S. Wilson, Dissertation, Yale University, 1936. ( S I H. S. Harned and B. B. Owen, "The Physical Chemistry uf 1;Ii.c.t r o l y t i c Solutions," Reinhold Publishing Corp.. Srw Ynrk, S Y . , 2d ed., 1950, pp. 9.5-114. ( 6 ) J . A. Gledhill and A . Patterson, J , P h y i . C ' h ~ n i , ,submitted f o r publication, Ilecember, 1952.
low field for the coriceiitratioii and temperature employed dnd the computed per cent. fractional high field conduct;ance, AX,'X0. Column 4 pertains t o the magnesium sulfate; column 5, t o t h e potassium chloride. Column 6 gives thc theoretical relative Wien effect for magnesium sulfate. Figure 1 is a plot of these data. I n the determination a t 5" a slightly higher concentration was employed, arid thrii two curves are drawn both for the experimental poitits; above, and the theoretical values, below. The higher curve5 correspond to the 5' measurements. S o difficulties in the performance of the conductaiicc cells when subjected to high field excitation or temperature cycliiig were observed.
I
'rAHLE
T H I HIC;H ~ FIELDCUXDUCTAKCE OF AQUEOVSSOLUTIONS OF bfACNESIVM S U L F A T E RELATIVE T O POTASSIUM C H L O R I D E F R O M 5 T O 55' .~
.I.
1 I g S 0 1 . 1 ,583 X I O molar Rn = 1842.5 ohms tCxoerimental results:
RV
1IgsOA
1835.u 1523.2 1817,:j 1811.Lj 1807.0 I803 . 1 1799.8 1798.2 1795 5 1793.4 1788.5 17-85 :i I 78'3. o 17x1 !)
AA XI,
c,
K C l : 2.312 X 10-4 molar KO = 175-1.0ohms Onsager-Wilson theory: \ f l MgSOi = 78, A0 KCI = 9 4 . 2 3 Azo = 74 5 Azo = 9 3 . 3 4 2X'Xu. A\
