Podcast
Questions and Answers
Which substance is likely to be reduced first when the potential of an electrode is moved to more negative potentials?
Which substance is likely to be reduced first when the potential of an electrode is moved to more negative potentials?
- The oxidant with the most negative reduction potential
- The oxidant with the highest reduction potential
- The oxidant with the least positive reduction potential
- The oxidant with the least negative reduction potential (correct)
What does current density depend on when discussing over-potential?
What does current density depend on when discussing over-potential?
- All types of overpotential combined (correct)
- Only charge-transfer overpotential
- Only mass-transfer overpotential
- Only overpotential associated with preceding reactions
In the context of electrocatalysis, what is meant by the 'power of electrode surface'?
In the context of electrocatalysis, what is meant by the 'power of electrode surface'?
- The conductivity of the electrode material
- The ability of the electrode to facilitate reactions (correct)
- The surface area of the electrode only
- The temperature of the electrode surface
What does the symbol 'O' represent in the general electrode reaction O + ne ↔ R?
What does the symbol 'O' represent in the general electrode reaction O + ne ↔ R?
Which of the following statements about charge-transfer overpotential is correct?
Which of the following statements about charge-transfer overpotential is correct?
What is the relationship between the potential of the Pt electrode and the onset of current flow?
What is the relationship between the potential of the Pt electrode and the onset of current flow?
In comparison to Pt, what characteristic does the mercury electrode exhibit regarding hydrogen evolution reaction?
In comparison to Pt, what characteristic does the mercury electrode exhibit regarding hydrogen evolution reaction?
What occurs if the potential of the Pt electrode is made more negative with respect to the Ag/AgBr reference electrode?
What occurs if the potential of the Pt electrode is made more negative with respect to the Ag/AgBr reference electrode?
What does the conventional notation denote regarding cathodic current?
What does the conventional notation denote regarding cathodic current?
What is the significance of E° for the H+/H2 reaction in this context?
What is the significance of E° for the H+/H2 reaction in this context?
How is the potential axis converted to EPt (V vs.NHE)?
How is the potential axis converted to EPt (V vs.NHE)?
What phenomenon occurs in a cell when no equilibrium can be achieved in one of the half cells?
What phenomenon occurs in a cell when no equilibrium can be achieved in one of the half cells?
Which statement best describes overpotential in the context of the mercury electrode?
Which statement best describes overpotential in the context of the mercury electrode?
Flashcards
Reduction Potential and Reduction Priority
Reduction Potential and Reduction Priority
In an electrochemical cell, the species with the least negative (most positive) reduction potential will be reduced first when the electrode potential is moved to a more negative value.
Overpotential
Overpotential
The overpotential is the difference between the actual electrode potential and the equilibrium potential. It represents the extra energy required to drive the reaction.
Mass Transfer Overpotential (ηmt)
Mass Transfer Overpotential (ηmt)
Mass transfer overpotential (ηmt) arises from the resistance to the movement of reactants and products to and from the electrode surface.
Charge-Transfer Overpotential (ηct)
Charge-Transfer Overpotential (ηct)
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Reaction Overpotential (ηrxn)
Reaction Overpotential (ηrxn)
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Cell Voltage
Cell Voltage
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Potential vs. Reference
Potential vs. Reference
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Half-cell reaction
Half-cell reaction
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Reduction
Reduction
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Oxidation
Oxidation
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Galvanic cell
Galvanic cell
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Electrolytic cell
Electrolytic cell
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Study Notes
Recap of Electrochemistry
- Examples of half-cell and full-cell reactions are included.
- Cell voltage and potential vs. reference are discussed.
- Examples of galvanic and electrolytic cell operation, based on prior concepts, are provided.
- Examples of cells where equilibrium cannot be achieved in one of the half-cells are shown.
Half-Cell Reactions and Oxidation/Reduction Currents
- Half-cell reactions are defined and include oxidation/reduction processes.
- A diagram illustrating a power supply connected to electrochemical cells is presented.
- The potential of a platinum electrode, related to hydrogen/hydrogen ions, is explained, along with cathodic and anodic current.
- Equations for half-cell reactions, including those for silver bromide, are given.
Half-Cell Reactions - Overpotential
- The same electrochemical cell with a mercury electrode instead of platinum is examined within a diagram.
- Comparing the cell with a platinum electrode, a diagram is included illustrating the current as a function of potential vs. NHE.
- Cases for cells without current under specific potential ranges are observed.
Adding Other Cations/Species to Electrolyte
- Adding other cations or species to the electrolyte affects the reduced substances' order of priority.
- The oxidant with the least negative reduction potential is reduced first.
- An equation related to the reaction when cadmium ions are added is included.
- Diagram explaining reduction/oxidation behavior when other species are introduced is given.
Rate and Pathway of Electrode Reaction
- The rate of a general electrode reaction with respect to time is described.
- The equation for current and how it relates to the number of moles electrolyzed is presented, along with defining terms for surface region and bulk solution for electrochemical reactions.
- The different types of over-potentials that affect the rate and pathways observed in electrochemical reactions are differentiated.
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Description
This quiz covers key concepts in electrochemistry, focusing on half-cell and full-cell reactions. It explores cell voltage, the operation of galvanic and electrolytic cells, and details oxidation and reduction processes in half-cells. Diagrams and equations are included to reinforce learning through visual representation.
