Journal of Solution Chemistry

, Volume 36, Issue 8, pp 1037–1046 | Cite as

A Determination of Standard Potentials and Related Primary pH Standards in the 50 Mass Percent (N-Methyl-2-Pyrrolidinone + Water) Mixture at Various Temperatures

  • Luigi Falciola
  • Patrizia R. Mussini
  • Torquato Mussini
  • Manuela Rossi
Original Paper


Following the IUPAC-endorsed procedure, the primary pH standards offered by the equimolal phosphate buffer (Na2HPO4 (0.01 mol⋅kg−1) + KH2PO4 (0.01 mol⋅kg−1)) in the (N-methyl-2-pyrrolidinone + water) solvent mixture of 50 mass percent composition at various temperatures have been determined from potential difference measurements with the reversible Harned cell. Since the essential prerequisite of the above procedure is the knowledge of the (hitherto unknown) standard potential difference of Harned’s cell, a parallel supplementary series of potential difference measurements has been carried out with the reversible cell, Pt|H2|HCl(m)|AgCl|Ag|Pt according to the classical thermodynamic procedure. The problem of comparability of the pH scale in the (N-methyl-2-pyrrolidinone + water) solvent with that in the pure water solvent is duly discussed in terms of primary medium effects.


(N-methyl-2-pyrrolidinone + water) mixtures Primary pH standards Ag–AgCl electrode Electrode potentials HCl activity coefficients pH scales comparison Primary medium effect 


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Luigi Falciola
    • 1
  • Patrizia R. Mussini
    • 1
  • Torquato Mussini
    • 1
  • Manuela Rossi
    • 1
  1. 1.Department of Physical Chemistry and ElectrochemistryUniversity of MilanoMilanItaly

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