Activity coefficients in sulphuric acid and sulphuric-acid-sodium-sulphate mixtures

✍ Scribed by H.E. Wirth

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 745 KB
• Volume: 16
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(71)80007-5

✦ Synopsis

Equations are developed that permit the calculation of the mean ionic activity coefllcients of Hf, H+, SO,'-(~1')

and of H +, HS04-(yl') from the measured practical activity coefficient of sulphuric acid, if cc (the fraction of total sulphate as SOP *-) and KS (the second dissociation constant of sulphuric acid) are known. On the assumption that the dependence of yl' on the ionic strength is similar to that of the activity coefficient of sodium sulphate, the constants in the equation -log yI' = 05065 ,IP/~/(~ + A$/%) +-BP +-Cpl have been determined to give agreement with observed isopiestic measurements. KS was re-evaluated from emf measurements in the literature ; K, = O-0102 is considered to be the best value. Estimates of a, yl', yI' and e (the stoichiometric dissociation quotient for HSO,-) are given for solutions of sulphuric acid and sulphuric-acid-sodium-sulphate mixtures in the ionic strength range o-4.0. The ionic strength dependence of yB ' is similar to that of the activity coefficient of hydrochloric acid.

R&xrm&-Connaissant

a (fraction du sulfate total a l'etat S04B-) et K9 (deuxieme constante de dissociation de l'gcide sulfurique), on peut obtenir des equations permettant de deduire les coefficients moyens d'activite ionique de H +, H+, SOhe-(rl') et de H+, HS04-(yr%') de la mesure du coefficient d'activite pratique de l'acide sulfurique.

En supposant que I'influence de la force ionique sur yl' est identique a celle du coefficient d'activite du sulfate de sodium les constantes de I'bquation: -log Yn' = 0,506s $'*(l + A$Ja) + BP + C@ ont 6% determin&x de man&e & s'accorder aux resultats de rnesures isopiestiques, K, a 6th reevalu6 & partir des donnees bibliographiques de f.e.m: Ka = 0,0102 est consider& comme sa meilleure valeur. On a estime a, yl', yB' et Q (quotient de dissociation stoechiombtrique pour HSO,-) pour des solutions d'acide sulfuriqu~sulfate de sodium, dans le domaine de force ionique O-4,0. L'influence de la force ionique sur yz' est identique a celle du coefficient d'activite de l'acide chlorhydrique.