Electrochemistry Module 1 Quiz

Questions and Answers

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?

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?

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?

Ag+ + 2e- → Ag(s) Signup and view all the answers

What characterizes crevice corrosion?

It occurs in small gaps or crevices between two pieces of metal. Signup and view all the answers

What is the role of Cu in the redox reaction with Ag+?

Cu is oxidized to Cu^2+ and facilitates the reduction of Ag+. Signup and view all the answers

What flow occurs in a galvanic cell to balance charge due to reduction?

NH4+ flows into the Ag+ beaker. Signup and view all the answers

Which statement is true about the electrolysis process?

It can produce gases or deposit metals. Signup and view all the answers

What is the role of the anode in a galvanic cell?

It is where oxidation occurs. Signup and view all the answers

What is denoted by a double vertical line in cell notation?

Salt bridge Signup and view all the answers

How is the standard electrode potential determined for a half-cell?

It is based on the comparison with a chosen standard electrode. Signup and view all the answers

Which of the following compounds acts as the anode in a lithium-manganese dioxide battery?

Lithium Signup and view all the answers

What does the equation $E^\circ = E^\circ_{anode} - E^\circ_{cathode}$ represent?

Standard cell potential calculation Signup and view all the answers

What is the significance of standard reduction potentials?

They indicate the voltage produced under standard conditions. Signup and view all the answers

What does a phase boundary represent in cell notation?

Transition between different states of matter Signup and view all the answers

In galvanic cells, cell potentials behave like which type of functions?

State functions Signup and view all the answers

What is one of the reactants used in a zinc-air battery?

Oxygen from the surrounding air Signup and view all the answers

Which of the following describes nickel-metal-hydride batteries?

They are designed for rechargeable use. Signup and view all the answers

In a lead-acid battery, which material is used as the anode?

Lead metal Signup and view all the answers

What type of electrolysis involves electrodes that are chemically inert materials?

Passive electrolysis Signup and view all the answers

What occurs during the reaction represented by $H_2 → 2H^+ + 2e^-$?

Oxidation Signup and view all the answers

Which of the following reactions occurs in active electrolysis?

Electrolytic reactions where electrodes participate Signup and view all the answers

Which of the following pairs is incorrectly matched regarding battery components?

Cathode - Nickel oxide (nickel-metal-hydride battery) Signup and view all the answers

What characteristic does lithium possess that makes it advantageous in batteries?

Large standard reduction potential Signup and view all the answers

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.