Cathode

Definition

A cathode is an electrode where reduction reactions occur, attracting cations in electrochemical cells. It plays a crucial role in processes like electrolysis and galvanic cells, where electrons are gained by the species at this electrode, allowing various chemical transformations to happen.

5 Must Know Facts For Your Next Test

1. In a galvanic cell, the cathode is positive because it attracts cations from the electrolyte.
2. During electrolysis, the cathode is where the reduction of ions takes place, leading to the deposition of solid material or gas formation.
3. The Nernst equation can be used to calculate the potential of the cathode under non-standard conditions.
4. In concentration cells, the cathode is determined by which half-cell has a higher concentration of cations, leading to spontaneous electron flow.
5. The performance and efficiency of batteries are significantly influenced by the materials used for the cathode.

Review Questions

• How does the function of a cathode differ between galvanic cells and electrolytic cells?
  • In galvanic cells, the cathode is the positive electrode where reduction occurs as it attracts cations from the electrolyte. Conversely, in electrolytic cells, the cathode is still where reduction happens but is considered negative because it is connected to a power source supplying electrons. This difference highlights how the same electrode can have different roles depending on the type of cell and its operating conditions.
• Analyze how changes in concentration affect the behavior of a cathode in a concentration cell.
  • In a concentration cell, the behavior of the cathode is heavily influenced by ion concentration. The side with higher ion concentration acts as the cathode, allowing it to attract cations and facilitate reduction. As concentrations equalize due to electron flow, the reaction dynamics at the cathode can shift, affecting overall cell performance and voltage output.
• Evaluate the impact of material selection for a cathode on electrochemical processes and device performance.
  • Material selection for a cathode is crucial as it directly influences reaction kinetics and overall efficiency in electrochemical processes. Different materials can have varying electron affinities and conductivity, affecting how well they facilitate reduction reactions. For example, using more conductive materials can improve battery performance by reducing internal resistance, while specialized materials can enhance specific reactions in electrolysis, making understanding these properties vital for optimizing devices like batteries and fuel cells.

Related terms

Anode: The electrode where oxidation reactions occur, releasing electrons into the circuit.

Electrolyte: A substance that contains free ions and conducts electricity when dissolved in a solvent or molten.

Galvanic Cell: An electrochemical cell that generates electrical energy from spontaneous chemical reactions, with distinct cathodes and anodes.