Electromotive force measurements at 25 degrees C of the transference cells Ag\AgCl\MeCl (m(2))\MeCl (m(1))\AgCl\Ag and MexHg1-x\MeCl (m(1))MeCl (m(1))\Me,Hg1-x (where Me = Li, Na, K, and Rb and MexHg1-x denotes a flowing Me-amalgam electrode at Me mole fraction x) have been made at various molalities m(2) > m(1) (with m(1) fixed and m(2) varied) in methanol + water solvent mixtures with methanol mass fractions w(m) up to 0.8. Supplementary emf measurements have been made of the cell Pt\LixHg1-x\LiCl (m(1))\AgCl\Ag\Pt to obtain the required activity coefficients for LiCl at methanol mass fractions w(M) = 0.2. The general trend of the ionic transference numbers of each MeCl is a t degrees(Me+) increase with w(M), which is much more pronounced for those Me+'s whose primary hydration sheaths are bigger (namely, Li+ and Na+). In particular, KCl becomes exactly equitransferent (t degrees(K+) = t degrees(Cl-) = 0.5, i.e. an ideal salt bridge) at w(M) approximate to 0.1, but at w(M) > 0.6 the KCl solubility becomes insufficient for a salt bridge function. The same drawback occurs also for RbCl, which is known to be the most closely equitransferent salt in water (t degrees(Rb+). = 0.5007). NaCl, which is quite unproposable as a salt bridge in water, may be useful at high methanol concentrations, as its ionic transference numbers would approach 0.5 at w(M) greater than or equal to 0.8.

Transference numbers of alkali chlorides and characterisation of salt bridges for use in methanol + water mixed solvent / A. Basili, T. Mussini, P.R. Mussini, S. Rondinini, B. Sala, A. Vertova. - In: JOURNAL OF CHEMICAL AND ENGINEERING DATA. - ISSN 0021-9568. - 44:5(1999 Oct), pp. 1002-1008. [10.1021/je9900979]

Transference numbers of alkali chlorides and characterisation of salt bridges for use in methanol + water mixed solvent

T. Mussini
Secondo
;
P.R. Mussini
;
S. Rondinini;A. Vertova
Ultimo
1999

Abstract

Electromotive force measurements at 25 degrees C of the transference cells Ag\AgCl\MeCl (m(2))\MeCl (m(1))\AgCl\Ag and MexHg1-x\MeCl (m(1))MeCl (m(1))\Me,Hg1-x (where Me = Li, Na, K, and Rb and MexHg1-x denotes a flowing Me-amalgam electrode at Me mole fraction x) have been made at various molalities m(2) > m(1) (with m(1) fixed and m(2) varied) in methanol + water solvent mixtures with methanol mass fractions w(m) up to 0.8. Supplementary emf measurements have been made of the cell Pt\LixHg1-x\LiCl (m(1))\AgCl\Ag\Pt to obtain the required activity coefficients for LiCl at methanol mass fractions w(M) = 0.2. The general trend of the ionic transference numbers of each MeCl is a t degrees(Me+) increase with w(M), which is much more pronounced for those Me+'s whose primary hydration sheaths are bigger (namely, Li+ and Na+). In particular, KCl becomes exactly equitransferent (t degrees(K+) = t degrees(Cl-) = 0.5, i.e. an ideal salt bridge) at w(M) approximate to 0.1, but at w(M) > 0.6 the KCl solubility becomes insufficient for a salt bridge function. The same drawback occurs also for RbCl, which is known to be the most closely equitransferent salt in water (t degrees(Rb+). = 0.5007). NaCl, which is quite unproposable as a salt bridge in water, may be useful at high methanol concentrations, as its ionic transference numbers would approach 0.5 at w(M) greater than or equal to 0.8.
Liquid-junnction potentials; reference value standards; organic-solvents; PH measurements; high permittivities; mixtures; thermodynamics; moderate; equitransference; minimization
Settore CHIM/02 - Chimica Fisica
ott-1999
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/155235
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