Standard pH values for potassium hydrogenphthalate reference buffer solutions in acetonitrile—water mixtures up to 70 wt% at various temperatures

✍ Scribed by Sandra Rondinini; Anna Nese

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 489 KB
• Volume: 32
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(87)85092-2

✦ Synopsis

Reference value standards, pHs, for 0.05 mol kg-X potassium hydrogenphthalate (KHPh) referencebuffer solutionsin 30, Mand 70 wt~Oacetonitrile-watermixed solventsat temperaturesfrom288.15 to 308.15 K have been determined from ernf measurements of the reversible cell Pt IAgtAgClIKHPh + KClIQuinhydronejPt, in which the H*-reversible quinhydrone electrode replaces the ill-behaving hydrogen electrode. Values of the first ionization constant of the o-phthalic acid (HsPh; benzene-l,2 dicarboxylic acid) in these mixed solvents have also been determined from analogous measurements. The consistency of the present results with the previously determined pHs values in 5, 15 and 30 wt "/, acetonitrile-water mixtures is analysed by multilinear regression of pHs as a function of both solution compositionand temperature. Thesesmoothed standard pHsvaluesareused tooptimize theparametersofan equation predicting pHs values in different aqueous organic solvents.