Electrochemical cell

An electrochemical cell is a device used for creating an electromotive force (voltage) and current from battery.

Overview

Each half-cell consists of an electrode with atoms, and an electrolyte with ions that undergo either salt bridge is often employed to provide electrical contact between two half-cells with very different electrolytes—to prevent the solutions from mixing. This can simply be a strip of filter paper soaked in saturated potassium nitrate (V) solution.

Each half-cell has a characteristic voltage. Different choices of substances for each half-cell give different potential differences. Each reaction is undergoing an equilibrium reaction between different oxidation states of the ions—when equilibrium is reached the cell cannot provide further voltage. In the half-cell which is undergoing oxidation, the closer the equilibrium lies to the ion/atom with the more positive oxidation state the more potential this reaction will provide. Similarly, in the reduction reaction, the further the equilibrium lies to the ion/atom with the more negative oxidation state the higher the potential.

This potential can be predicted quantitatively through the use of hydrogen). The difference in voltage between electrode potentials gives a prediction for the potential measured. Spontaneity of a chemical reaction is determined by the overall cell potential E^o. If E^o>0, the reaction is spontaneous and if E^o<0, the reaction will not be spontaneous.

The potential window is the electrochemical voltage range between which a substance does not get oxidized or reduced.

Electrochemical cell

Overview

Cell types

See also