Thermodynamics of aqueous KOH over the full range to saturation and to 573 K

The pH of Aqueous NaOH/KOH Solutions: A Critical and Non-trivial Parameter for Electrocatalysis

“…These measurements always contain an error at higher ionic strengths (>0.1 mol/kg) as the potential difference between the electrode processes can only be obtained knowing single-ion activities already to either calculate the liquid junction potential or the potential of the reference electrode (see footnotes − ). ,,− In the 1940s, Åkerlöf and co-workers determined the activity coefficients of aqueous NaOH and KOH experimentally (0–70 °C, 0–17 mol/kg) through electromotive force measurements of RHEs. , This experimental data agrees to 2% with the Debye–Hückel theory for ionic strength below 0.1 mol/kg and to other experimental data by Harned and co-workers performed in the 0.1–4.0 mol/kg range . Further, this data is adapted in important tabulated data sets such as the CRC Handbook of Chemistry and Physics , , and was used as experimental verification of extended forms of the Debye–Hückel equation and the Pitzer equations . To the best of our knowledge, no newer γ Na/KOH measurements exist.…”

“…14 Further, this data is adapted in important tabulated data sets such as the CRC Handbook of Chemistry and Physics, 12,24 and was used as experimental verification of extended forms of the Debye− Huckel equation 25 and the Pitzer equations. 26 To the best of our knowledge, no newer γ Na/KOH measurements exist. Further, due to the fluid amalgam separator in Åkerlof's cell, the liquid junction potential should be small.…”

A Simple G-Excess Model for Concentrated Aqueous Electrolyte Solutions

“…As a matter of fact, experimental data for all the 1–1 electrolytes were obtained from Hamer and Wu . Only in the case of KOH, were the experimental data of Li and Pitzer also considered to test the modeling capabilities of the present approach over a wide temperature range (from 0 to 300 °C) and at very high molality (up to 83.263 M).…”

“…It is now worthwhile to verify the abilities of the present three-parameter model in accurately representing the experimental data of a particular aqueous electrolyte system at temperatures other than 25 °C. The experimental γ ±, m and φ data of KOH in water measured by Li and Pitzer at 0, 25, 50, 100, 150, 200, 250, and 300 °C were chosen for this purpose. As previously done, the three model parameters ( k 0 , α s,w , and β s,w ) were obtained by fitting the experimental γ ±, m data at each temperature.…”

Thermodynamics of Aqueous NaOH over the Complete Composition Range and to 523 K and 400 MPa

“…Since NaOH(aq) is a strong electrolyte to at least 573 K, the fully ionized basis is appropriate for that range. Equations of this type combining a Debye−Hückel term with Margules terms have now been used successfully for several systems. − The range of experimental data for NaOH−H 2 O to 523 K and 400 MPa is exceptionally extensive; thus, it is a challenge to provide an accurate representation in a form that also allows convenient application to multicomponent systems. The form of equation presented by Clegg and Pitzer 7 and Clegg et al .…”