Cathode

Definition

A cathode is an electrode in an electrochemical cell where reduction occurs, meaning it gains electrons. In a galvanic cell, it is the positive electrode, while in an electrolytic cell, it is the negative electrode. The movement of electrons towards the cathode and the reactions that occur at this electrode are crucial for understanding how electrochemical processes function.

5 Must Know Facts For Your Next Test

1. In a galvanic cell, the cathode is where the positive ions in the solution gain electrons to form neutral atoms or molecules.
2. During electrolysis, the cathode attracts cations, which are positively charged ions that move toward the negative electrode.
3. The standard reduction potential of a cathode is a key factor in determining its efficiency and effectiveness in electrochemical reactions.
4. In practical applications, such as batteries and electroplating, the materials used for cathodes can significantly impact the performance and longevity of the device.
5. Understanding the function of the cathode is essential for optimizing processes in fuel cells, which rely on efficient electron transfer to generate energy.

Review Questions

• How does the role of the cathode differ between galvanic cells and electrolytic cells?
  • In galvanic cells, the cathode is the positive electrode where reduction takes place, and electrons flow into it from the external circuit. In contrast, in electrolytic cells, the cathode serves as the negative electrode where reduction also occurs, but it requires an external source of energy to drive the reaction. This fundamental difference highlights how electrochemical cells function in generating electrical energy versus using it.
• Discuss how the standard reduction potential affects the choice of materials for a cathode in electrochemical cells.
  • The standard reduction potential indicates how easily a substance can be reduced at the cathode. Materials with higher standard reduction potentials are more favorable as cathodes because they can attract electrons more effectively, enhancing their capacity to undergo reduction reactions. Therefore, selecting materials based on their standard reduction potentials is crucial for optimizing battery performance and efficiency.
• Evaluate the importance of electron transfer at the cathode in applications like fuel cells and electroplating.
  • Electron transfer at the cathode is vital for both fuel cells and electroplating because it directly influences efficiency and product quality. In fuel cells, efficient electron transfer leads to better energy conversion from chemical to electrical energy. In electroplating, the quality of deposition relies on controlled electron flow at the cathode to ensure uniform coating. Understanding these processes can lead to advancements in technology and more sustainable practices.

Related terms

Anode:

The electrode in an electrochemical cell where oxidation occurs, meaning it loses electrons.

Electrolyte: A substance that produces an electrically conducting solution when dissolved in a solvent, facilitating the flow of ions in an electrochemical cell.

Redox Reaction: A chemical reaction involving the transfer of electrons between two species, encompassing both reduction (gain of electrons) and oxidation (loss of electrons).