Podcast
Questions and Answers
What occurs during galvanic corrosion?
What occurs during galvanic corrosion?
- It happens when a metal is exposed to air.
- It involves different metals in contact with each other in electrolyte. (correct)
- Corrosion occurs exclusively at the edges of a metal.
- Corrosion occurs evenly over a large surface area of a metal.
In a redox reaction, which species is oxidized?
In a redox reaction, which species is oxidized?
- The species that loses electrons. (correct)
- The species that remains unchanged.
- The species that has the highest standard electrode potential.
- The species that gains electrons.
What does a higher standard reduction potential indicate?
What does a higher standard reduction potential indicate?
- It does not affect the redox reaction.
- A stronger ability to gain electrons. (correct)
- A weaker ability to gain electrons.
- A stronger ability to lose electrons.
In the electrolysis of silver nitrate (AgNO3), which reaction at the cathode is expected?
In the electrolysis of silver nitrate (AgNO3), which reaction at the cathode is expected?
What characterizes crevice corrosion?
What characterizes crevice corrosion?
What is the role of Cu in the redox reaction with Ag+?
What is the role of Cu in the redox reaction with Ag+?
What flow occurs in a galvanic cell to balance charge due to reduction?
What flow occurs in a galvanic cell to balance charge due to reduction?
Which statement is true about the electrolysis process?
Which statement is true about the electrolysis process?
What is the role of the anode in a galvanic cell?
What is the role of the anode in a galvanic cell?
What is denoted by a double vertical line in cell notation?
What is denoted by a double vertical line in cell notation?
How is the standard electrode potential determined for a half-cell?
How is the standard electrode potential determined for a half-cell?
Which of the following compounds acts as the anode in a lithium-manganese dioxide battery?
Which of the following compounds acts as the anode in a lithium-manganese dioxide battery?
What does the equation $E^\circ = E^\circ_{anode} - E^\circ_{cathode}$ represent?
What does the equation $E^\circ = E^\circ_{anode} - E^\circ_{cathode}$ represent?
What is the significance of standard reduction potentials?
What is the significance of standard reduction potentials?
What does a phase boundary represent in cell notation?
What does a phase boundary represent in cell notation?
In galvanic cells, cell potentials behave like which type of functions?
In galvanic cells, cell potentials behave like which type of functions?
What is one of the reactants used in a zinc-air battery?
What is one of the reactants used in a zinc-air battery?
Which of the following describes nickel-metal-hydride batteries?
Which of the following describes nickel-metal-hydride batteries?
In a lead-acid battery, which material is used as the anode?
In a lead-acid battery, which material is used as the anode?
What type of electrolysis involves electrodes that are chemically inert materials?
What type of electrolysis involves electrodes that are chemically inert materials?
What occurs during the reaction represented by $H_2 → 2H^+ + 2e^-$?
What occurs during the reaction represented by $H_2 → 2H^+ + 2e^-$?
Which of the following reactions occurs in active electrolysis?
Which of the following reactions occurs in active electrolysis?
Which of the following pairs is incorrectly matched regarding battery components?
Which of the following pairs is incorrectly matched regarding battery components?
What characteristic does lithium possess that makes it advantageous in batteries?
What characteristic does lithium possess that makes it advantageous in batteries?
Study Notes
Types of Corrosion
- Uniform corrosion occurs evenly over a large surface area of metal.
- Galvanic corrosion happens when two different metals are in contact in an electrolyte.
- Crevice corrosion arises in small gaps between touching metal pieces.
Oxidation-Reduction Reactions
- Oxidation is defined as the loss of electrons; reduction is the gain of electrons.
- Silver ion reduction example:
- ( \text{Ag}^+ + e^- \rightarrow \text{Ag(s)} )
- Copper oxidation example:
- ( \text{Cu(s)} \rightarrow \text{Cu}^{2+} + 2e^- )
Galvanic Cells
- Oxidation occurs at the anode; reduction occurs at the cathode.
- NH4+ ions flow to offset silver ions removed, while Cl- ions offset copper ions produced.
- Cell notation format:
- Left side includes anode and right side includes cathode, e.g., ( \text{Cu(s)} | \text{Cu}^{2+} (1 \text{ M}) || \text{Ag}^+ (1 \text{ M}) | \text{Ag(s)} ).
Measuring Cell Potentials
- Standard Hydrogen Electrode (SHE) is assigned zero volts.
- All other half-cells are measured against this reference.
Standard Reduction Potentials
- Standard reduction potentials are crucial for calculating cell potentials and predicting reaction spontaneity.
- ( E^{\circ}{cell} = E^{\circ}{cathode} - E^{\circ}_{anode} )
Batteries
- Primary cells include lithium and alkaline batteries; characterized by non-rechargeability.
- Secondary cells (e.g. nickel-metal-hydride) can be recharged and include lead-acid batteries regularly found in vehicles.
Fuel Cells and Electrolysis
- Fuel cells convert chemical energy to electrical energy efficiently.
- Electrolysis can be passive (inert electrodes) or active (reacting electrodes).
Electrolysis Processes
- Example of electrolysis for silver plating:
- ( \text {Ag(s)} + 2 \text {CN}^- \right arrow \text {Ag(CN)} ^- + e^- )
- Current, charge, and time relation:
- Faraday's law correlates current to the amount of substance deposited.
Engineering Design Considerations
- Lithium-ion batteries benefit from high standard reduction potential of Li^+/Li.
- Both lithium and carbon materials are lightweight, optimizing energy density.
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Description
Test your knowledge on corrosion types and the chemical reactions responsible for them. This quiz covers redox processes, balancing half-reactions, and calculating cell potentials under various conditions. Assess your understanding of electrochemistry principles essential for engineers.
