iiieasurenients made with a glass electrode and a Imtentiometer (radiometer) of inferior accuracy (0.3 to 0.6 mv. i In Table I1 Grunwald's values a t low ionic strength have been compared with our values. Here C, and Ce are the stoichiometric concentrations of acetic acid a t the inflection point and eyuivalent poirit, respectively. I is the ionic strength of the solution. Our values deviate from each other much less than those of Grunwald, owing partly to the somewhat greater accuracy of the potentiometer used by us. For the thermodynamic constant our values give 1.754 X lop5 in perfect agreement with the value of Harned arid Ehlersg 1.753 X lo-*? (20"). Because this differential method is based on the iiiedsurenient of small potential differences, great Accuracy of the potentiometer is essential. On the other hand the accurate measurement of the small potential jumps is possible because the uncontrolled factors, which often disturb thc potentiometric measurements, very largely cancel each other out in a differential method in which the tneasuretiients are carried out under constant conditions. '$3) H. b Harned arid R (1'1'32), 66, 6.52 (19311
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his
JowR\r%i
64, 1130
Our measurements given here were made with a potentiometer of the Cambridge Instrument Co., slidewire-type, graduated in 0.2-mv. intervals and with an accuracy of 0.1 mv. We have since used the Vernier potentiometer of the Cambridge Instrument Co., graduated on 0.01-mv. intervals and a potentiometer of Leeds-Northrup graduated o n 0.0e5-niv.intervals and with an accuracy of 0.01 mv. Now the error due to the potential nieasurement is of the same order of magnitude as the other experimental errors. Sext to the potential jumps, the accuracy in measuring the volume increment of the reagent added is important. M?th our drop m e t h ~ d , ~126~ , p if a micro-buret is used, an accuracy of 0.001 ml. may easily be reached. An accuracy of 0.0002 ml. may be attained with micrometer pipets. This corresponds to the accuracy obtained with the accurate potentiometers described. These technical improvements are itiiportaiit 111 the studies on the dissociation constants in niixtures of electrolytes being made in this Laboratory. Further, we are investigating the dissociation of bases in acetic acid solutions by means of our method described above. HEISISKI, FIULAVD
/clJS 1 K i t J U I IOf 1'KOM TIIE ~SClS cl3!3MISl'RY
L.IUUK.Z'I'lIRY
0 1 3 l'L'LASIi
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Inorganic Complex Compounds Containing Polydentate Groups. VIII. Complexes with 2-Nitroso-1-naphtholia BY II.\XS
B.
JOXASSEN AND LVINSTON
Zirconium(1V)
K. DEMONSABERT'~
RECEIVED JANUARY 2, 1952 The coinplexes formed between 2-nitroso-1-naphthol and zirconium( I\') have been investigated in mixtures of water aud ethanol and water and dioxane in the absence and presence of HCIO,. I t has been found that in the absence of HCI04 a one-to-one complex forms, whereas in solutions 3 dl or larger in HCIO, and 3 X 10-3 JI Zr(1V) a one-to-four complex is formed. The pK instability values have been determined: for thc one-to-one coiiiplex in ethanol-water it is 3.7 and for the one-to-four complex in 505. dioxane-water it is 11.6
Introduction Distribution studies by Connick and AlcT'ey' show that Z r f 4 or (ZrOH) +-3 ions are present i n 2 -I( perchloric acid and low zirconium(1V) ion colicentration. Connick and Iieas3 report the formation of zirconium polymers a t zirconium ion concentrations of 2 X lou3 -I[ in 2 M HC104 and 2 X 10 - I -2% in 1 116 HClOb solutions. Thamer and Voigt4 have investigated zirconium cliloranilate complexes in 1 :If and 3 -11 HClO4 solutions and find evidence to support a me-to-om and a one-to-two monomeric complex. Bellucci and Savoia,; reported that 1 -nitroso-?naphthol precipitates zirconium (IV) in acid solution forming ZrO(CloH~(NO)O)eand that the (1) ( a ) Presented before t h e Division of Physical a n d Inorganic Chemistry at t h e 1 2 1 s Meeting of t h e American Chemical Society, Buffalo, N. Y.,March 23-27, 1952. (b) Department of Chemistry, I.nyola University of t h e South, New Orleans, Louisiana. ( 2 ) R. E. Connick and W . H. McVey, THISJ O U R X A L , 71, 3182 fl!llcI) ::1
I
