A Spectrophotometric Study of the Hydrolysis Products, Some Possible Complexes and Metal Salts of Fluoroboric Acid¹

Abstract

In their paper Drenan and Hill6 give two calculated values for M in the case of hydrogen iodide adsorbed on graphite a t 81.33' K. M is equal to 16.99 if the adsorption is non-localized and 2.16 if it is localized. As both these values are greater than unity the entropy of adsorption to the standard SO = SI must be less than the entropy of liquefaction which is an interesting and unexpected result, especially in the case of localized adsorption. Summary Equations are derived showing that the BET constant albz/azbl is unity only when the differential entropy of adsorption to a standard state on the surface defined by SO = SI (the bare fraction of the surface being equal to the fraction covered by one layer of molecules) is equal to the entropy of liquefaction of the adsorbate. It is also shown from published results that the value of albn/a&l may range a t least from to 10, and that the single isotherm method of determining heats of adsorption can only be used when the entropy of adsorption is known. CAMBRIDGE, ENGLAND RECEIVED MAY 8, 1950 In the course of an investigation of fluoroboric of zinc fluoroborate was prepared from the pure hexahyacid, spectrophotometric analysis was studied as drate. Technical lead fluoroborate solution (50.7%), a possible method of identification and analysis purified W I I ) fluoroborate solution (47.7%) and cadmium fluoroborate solution (50.8%) were used as received.Of the its products, and its The fluoroborate salts and solutions were very kindly compounds. An attempt was made also to furnished by the General Chemical Division, Allied determine the extent of complex formation, if Chemical and Dye Corporation. any, of the fluoroborate ion and Some of its Procedure and Results.-To investigate the possible hydroxy acids. cases, the method of formation of complexes between fluoroboric acid and cobalt(I1) or nickel(I1) , respectively, three solutions were continuous variations as by Jobs and prepared for each ion as described under Materials. The improved by Vosburgh and Cooper4 was applied nitrate salts were used in each case, because in dilute in the study of possible complexes. The characteristic spectra of two hydrolysis products of fluoroboric acid have been obtained, and the general lack of any complexing tend-O.5O ~ ency has been demonstrated. 0.40 -& 2 U Experimental .* Measurements.-Light absorption measurements $ 0.30 were made with a Beckman model DU spectrophotometer. Quartz or corex cells (1-cm.) were used, and all readings were made at room tem-Materials.-C. P. samples of hydrated cobalt and nickel nitrates were dissolved to give 0.1 M solutions (1) in water, (2) in 7.7 M hydrochloric acid and (3) in 42% aqueous fluoroboric acid. A 0.2 M o , o~ . solution of cupric sulfate was prepared from the C. P. hydrate. C. P . chromium metal was treated with 60% perchloric acid, 42% fluoroboric acid, and 400 500 600 anhydrous H[BFz(OH)Z] to give solutions 0.03,0.07 and 0.02 M , respectively, in chromium(II1) ion. H[BFz(OH)z] was prepared by the method of Soiva, Fig. ~.-AbsorPtio...

Light Absorption Spectrometry

“…The concept of an "interaction" complex has been proposed by McConnell and Davidson (171,173) in a study of the optical interaction between chloro complexes of copper(I) and eopper(II) in solution. The method was applied to iron(II and III) systems (172), tin(II and IV) systems ( 47 acids with various metals (178); pyramidone with aluminum, chromium, and iron (109); citric acid with uranium (84); sulfosalicylic acid with iron(III) (89); alkannin and naphthazarin (270) and quinalizarin (181) with beryllium; several organic compounds with different metals (156, 157); and thenoyltrifluoroacetone with thorium (70), Papers on systems of a somewhat different nature deal witli iodine in acetone (33); cobalt(II), nickel(II), and chromium(III) in fluoboric acid (238); manganese(III) in hydrochloric acid (126); and iron(III) in the perennial thiocyanate solution (57).…”