Potentiometric determination of the apparent dissociation constants and free energy of transfer of tris (hydroxymethyl) aminomethane buffer in various hydroorganic media

• Autorzy: Anwar Z. M.
• Języki publikacji: EN

Abstrakty

EN

The apparent dissociation constant of tris (hydroxymethyl) aminomethane (Tris-buffer) was determined at (25.0 š 0.1)°C and / = 0.1 mol dm(-3) KNO3 by po-tentiometric pH titration in pure water and different hydroorganic solvent media. The organic solvents used were methanol, ethanol, N, N-dimethylformamide (DMF), acetone and dioxane. pKa(2) changes with an increase in the concentration of organic solvent. The results are discussed in terms of solvent characteristics. Solvent basicity and stabilization of the conjugate acid free base by hydrogen bonding interactions in hydroorganic solvent media relative to pure aqueous media as well as proton-solvent interaction play an important role in the dissociation equilibrium of the Tris buffer. The free energy of transfer of the protonated form of the Tris buffer to the neutral from water to mixtures of water + organic solvents are calculated.

Słowa kluczowe

EN

apparent dissociation; free energy; tris (hydroxymethyl) aminomethane; buffer

PL

dysocjacja; energia swobodna; aminometan; roztwór buforowy

• Wydawca: Centrum Upowszechniania Nauki PAN
• Czasopismo: Bulletin of the Polish Academy of Sciences. Chemistry
• Rocznik: 2003
• Tom: Vol. 51, No. 3-4
• Strony: 195--205
• Opis fizyczny: Bibliogr. 21 poz.

Twórcy

autor

Anwar Z. M.

• Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt