Standard Electrode Potential

Definition

Standard electrode potential is the measure of the ability of a half-cell to gain or lose electrons under standard conditions, typically 25°C, 1 M concentration of ions, and 1 atm pressure for gases. This value is expressed in volts and serves as a reference point for comparing the reactivity of different electrodes in electrochemical cells. Understanding this concept is essential for determining the direction of electron flow and the overall cell potential during electrochemical reactions.

5 Must Know Facts For Your Next Test

1. The standard electrode potential is determined under standard conditions, making it easier to compare the tendencies of different half-cells to undergo oxidation or reduction.
2. A positive standard electrode potential indicates a greater tendency for reduction, while a negative value suggests a stronger tendency for oxidation.
3. Standard electrode potentials can be used to calculate the overall cell potential (E_cell) using the formula E_cell = E_cathode - E_anode.
4. The values of standard electrode potentials are tabulated for various half-reactions, allowing for quick reference when analyzing electrochemical cells.
5. When combining half-reactions with different standard electrode potentials, the one with the higher potential will act as the reduction half-reaction in an electrochemical cell.

Review Questions

• How does standard electrode potential influence the direction of electron flow in an electrochemical cell?
  • Standard electrode potential plays a crucial role in determining the direction of electron flow in an electrochemical cell by indicating which half-cell will undergo reduction and which will undergo oxidation. The half-cell with the higher standard electrode potential will attract electrons from the other half-cell, thereby driving the overall reaction. By comparing the standard potentials, we can predict how the cell will operate and which reactions will occur at each electrode.
• Discuss the significance of standard hydrogen electrode (SHE) in measuring standard electrode potentials.
  • The standard hydrogen electrode (SHE) serves as a fundamental reference point for measuring standard electrode potentials. By convention, SHE is assigned a potential of 0 volts, enabling other half-reactions to be compared directly against it. This standardization is important because it allows chemists to assess the relative strength of various oxidizing and reducing agents based on their measured potentials against SHE, facilitating easier calculations and predictions about electrochemical behavior.
• Evaluate how changes in concentration or temperature might affect standard electrode potentials and their practical applications.
  • Standard electrode potentials are measured under specific conditions (25°C and 1 M concentrations), so deviations from these conditions can significantly alter their values. For example, increased concentrations of reactants in a half-cell can shift equilibrium and modify reduction potentials due to Le Chatelier's principle. This can affect practical applications such as batteries and corrosion prevention, where real-world conditions may differ from standard conditions. Understanding these variations is crucial for optimizing performance and efficiency in electrochemical systems.

Related terms

Electrochemical Cell: A device that generates electrical energy from chemical reactions or facilitates chemical reactions through the introduction of electrical energy.

Reduction Potential: The tendency of a chemical species to acquire electrons and be reduced, measured relative to the standard hydrogen electrode.

Standard Hydrogen Electrode (SHE): A reference electrode with a standard electrode potential defined as 0 volts, used to measure the potentials of other electrodes.