Static dielectric constants of acetonitrile/water mixtures in the whole composition range and within the temperaturerange from (15 to 60)
![](/images/entities/deg.gif)
C have
been measured. The values were fitted to a unique equation as a simultaneousfunction of temperature and acetonitrile composition. Densities of these mixtures at temperatures from (5 to 55)
![](/images/entities/deg.gif)
C and different compositions have
been collected from the literature. The complete data set was critically analyzed,the outliers were excluded, and the remaining values were also fitted to a unique equation as a function oftemperature and acetonitrile composition. From the dielectric constants and densities, the activity coefficients ofions can
be calculated
by means of the De
bye-H&
uuml;ckel approach, allowing the study of the ionic equili
bria anddetermination of reference pH values or acidity constants in any acetonitrile/water mixture at any temperaturewithin the studied range.