A sensor for the in situ determination of acidity levels in concentrated sulfuric acid

A potentiometric method at imposed weak current between two paste electrodes, ferrocene and chloranil, permits the in situ determination of sulfuric acid concentrations (0.5–11.0 M). The different factors affecting the potential at imposed current as current intensity, temperature and H+ ion concentration are studied. The potentials measured between ferrocene and chloranil electrodes are directly linked to the acid concentration. The acidity Ri(H) function, which represents the determination of the H+ activity has been determined and compared to Strehlow Ro(H), Janata HGF and Hammet Ho functions. Ri(H) is numerically equal to the thermodynamic Ro(H).