ISSN:
1572-8927
Schlagwort(e):
pH standards
;
aqueous—organic solvents
;
medium effects
;
ionization constants
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract Determination of primary standards for pH measurements in glycerol + water solventmixtures has been carried out based on reversible emf measurements of the cellPt|H2|KHPh (m PS) + KCl (m Cl)|AgCl|Ag|Ptwhere KHPh denotes the potassium hydrogen phthalate buffer solution of molalitym PS = 0.05 mol-kg−1, at glycerol mass fractions w G = 0.2 and 0.4, within thetemperature range −10 to 40°C. A multilinear regression procedure as a functionof electrolyte molality, glycerol mass fraction w G, and temperature T has beenapplied for the data processing leading to the values of primary standards pHPS.These can be represented by the following regression equationpHPS = (4.007037±0.001113) + (3.55844±0.01776)x G+(0.39622±0.01410)z + (4.3084±0.3377)z 2− (50.66±10.53)x G z 2 + (457.10±78.48)x G 2 z 2where z = (T − 298.15)/298.15. Parallel values of the first ionization constantof o-phthalic acid (H2Ph; benzene-1,2-dicarboxylic acid, the parent acid of KHPh),which are essential for the above calculations, have been determined fromreversible emf measurements of the cellPt|H2|H2Ph (m 1) + KHPh (m 2) + KCl (m 3)|AgCl|Ag|Ptover the range of solvent composition and temperatures mentioned above.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1026432128009
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