What is a cathode in electrochemical cells?

In an electrochemical cell, the cathode is defined as the negative pole or electrode. In the context of electrochemical reactions, the cathode is where reduction occurs, which means it is the site at which electrons are gained. This characteristic is fundamental to the operation of both galvanic (voltaic) and electrolytic cells. In a galvanic cell, the cathode attracts cations from the solution, which accept electrons and, thus, undergo reduction. Conversely, in an electrolytic cell, the cathode receives electrons from an external power source, facilitating the reduction process.

Understanding the role of the cathode also requires a grasp of how it functions in relation to the anode, which serves as the positive pole where oxidation occurs. The definition and function are critical in electricity flow, as electrons are drawn toward the cathode from the anode, establishing the essential reactions within the cell necessary for generating or utilizing electrical energy.

The other choices relate to concepts in electrochemistry but do not accurately define the cathode's function and role, making them less relevant in the context of identifying the cathode.