Thermodynamics of the Second Dissociation Constant of N-tris[Hydroxymethyl]-4-amino-butanesulfonic Acid (TABS) from 5 to 55°C

Autor: Roy, Rabindra, Roy, Lakshmi, Simon, Ashley, Moore, Andrew, Seing, Lydia, Richards, Sarah, Craig, Heather, Childers, Benjamin, Tabor, Bennett, Himes, Curtis, Viele, Katherine
Zdroj: Journal of Solution Chemistry; April 2004, Vol. 33 Issue: 4 p353-364, 12p
Abstrakt: N-tris[Hydroxymethyl]-4-aminobutanesulfonic acid (TABS) has been investigated for the determination of the values of the second dissociation constant, pK2, in water at 12 temperatures in the range 5–55°C, including 37°C. This zwitterionic compound is useful as a secondary pH standard in the range of pH (7–9) for physiological applications. The electromotive force (emf) measurements have been carried out using a hydrogen gas electrode and a silver–silver chloride electrode. The values of pK2are fitted as a function of temperature with the following results: pK2= 1671.305/T+14.8737−2.04383 ln T, where Tis the thermodynamic temperature in Kelvins. The experimental values of pK2are 8.834 ± 0.0005 and 8.539 ± 0.0004 at 25 and 37°C, respectively. The related thermodynamic quantities, Δ G°, Δ H°, Δ S°, and Δ Cp° characterizing the dissociation process have been derived from the pK2and its temperature coefficients.
Databáze: Supplemental Index