Which equation describes the potential that develops at the surface of an ion-selective electrode?

The Nernst equation is fundamental to understanding the potential that develops at the surface of an ion-selective electrode. This equation relates the concentration of an ion in solution to the electric potential generated across a membrane that is selective to that ion. Specifically, the Nernst equation provides a quantitative relationship that describes how the potential changes with varying concentrations of ions, allowing for the calculation of the electrode's response to those ions.

In the case of ion-selective electrodes, the Nernst equation predicts how the voltage signal measured by the electrode will correspond to the activity (or effective concentration) of a specific ion. This is crucial for the accurate detection and measurement of ion concentrations in various samples because the potential difference created at the electrode surface is directly influenced by the concentration gradient of the ion across the membrane.

Other choices, such as the van Deemter equation, which is related to the efficiency of chromatographic columns, the van Slyke equation, which pertains to the measurement of gas solubility and partial pressures, or the Henderson-Hasselbalch equation, which is used to calculate the pH of buffered solutions, are not relevant to the functioning and principles governing ion-selective electrodes. The unique relationship that the Nernst equation captures