Cathode

Definition

The cathode is the electrode in an electrochemical cell where reduction occurs, meaning it gains electrons. This electrode plays a crucial role in galvanic cells, which convert chemical energy into electrical energy, as well as electrolytic cells, where electrical energy drives a non-spontaneous reaction. The cathode is essential for understanding how these systems operate, as it interacts with ions in the electrolyte to facilitate electron flow.

5 Must Know Facts For Your Next Test

1. In a galvanic cell, the cathode is connected to the positive terminal of the external circuit, attracting cations from the electrolyte.
2. The cathode undergoes reduction, which involves a gain of electrons during the electrochemical reaction.
3. In electrolytic cells, the cathode is the negative electrode, and it attracts cations, where reduction still takes place.
4. The materials used for the cathode can vary widely depending on the type of electrochemical reaction and desired efficiency.
5. Identifying the cathode in any electrochemical cell requires knowing whether the cell is operating under galvanic or electrolytic conditions, as its role changes based on the type of cell.

Review Questions

• How does the role of the cathode differ between galvanic and electrolytic cells?
  • In galvanic cells, the cathode is where reduction takes place and is connected to the positive terminal, while in electrolytic cells, it serves as the negative electrode where reduction also occurs. Despite both types of cells having a cathode that facilitates electron gain through reduction, their roles are defined by the overall process of the cell—spontaneous for galvanic cells and non-spontaneous for electrolytic cells. This distinction is key to understanding their functionality and applications.
• Explain how the composition and material of a cathode can affect its performance in an electrochemical cell.
  • The material used for a cathode significantly influences its performance due to factors such as conductivity, stability, and catalytic activity. A well-chosen cathode material can enhance electron transfer rates, improve reaction efficiency, and increase overall cell voltage. For instance, using noble metals like platinum may lead to higher efficiencies in certain reactions but can be costly. Understanding these properties helps in selecting suitable materials for specific applications.
• Evaluate how changes in temperature can impact the behavior of a cathode in an electrochemical cell.
  • Temperature changes can have profound effects on a cathode's behavior in an electrochemical cell by altering reaction kinetics and ion mobility. Higher temperatures generally increase reaction rates due to enhanced molecular activity, potentially improving current output at the cathode. However, if temperatures become too high, they can lead to side reactions or degradation of materials. Thus, evaluating temperature effects is crucial for optimizing cell performance and ensuring long-term stability.

Related terms

Anode: The anode is the electrode in an electrochemical cell where oxidation occurs, losing electrons to the external circuit.

Galvanic Cell: A galvanic cell is an electrochemical cell that generates electrical energy from spontaneous chemical reactions.

Electrolyte: An electrolyte is a substance that contains free ions and conducts electricity when dissolved in water or melted.