Electrochemical Cells Quiz
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Electrochemical Cells Quiz

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Questions and Answers

Which cation will be reduced first at the cathode in an electrolytic cell containing multiple cations?

  • The one with the lowest standard reduction potential
  • The one with the highest concentration in the solution
  • The one with the highest molecular weight
  • The one with the greatest positive standard reduction potential (correct)

    • In the context of electrolysis, what does the anode do?

  • Sustains the flow of electrons towards the power source
  • Reduces metal cations to their elemental form
  • Oxidizes and replaces the metal cations in solution (correct)
  • Increases the concentration of cations in solution

    • What is the relationship between the time, current, and moles of electrons in electrolysis?

  • Moles of electrons are inversely proportional to current
  • Moles of electrons are directly proportional to both current and time (correct)
  • Longer time and higher current always produce more metal regardless of the cell's voltage
  • Moles of electrons are independent of time and current

    • How is Faraday's constant significant in electrolysis calculations?

    <p>It converts charge in coulombs to moles of electrons</p> Signup and view all the answers

    In an electrolytic cell, which condition must be met for a reaction to occur spontaneously?

    <p>The standard cell potential must be positive</p> Signup and view all the answers

    What is the role of current in an electrolytic cell?

    <p>It provides the energy needed to drive non-spontaneous reactions</p> Signup and view all the answers

    What is the primary role of a salt bridge in an electrochemical cell?

    <p>To maintain charge balance and complete the circuit</p> Signup and view all the answers

    Which statement correctly describes the flow of electrons and ions in an electrochemical cell?

    <p>Electrons flow along the external circuit whereas ions move through the salt bridge</p> Signup and view all the answers

    What defines the cell potential in a voltaic cell?

    <p>The difference in potential energy between the anode and cathode</p> Signup and view all the answers

    How does increasing the electrode surface area affect the current in an electrochemical cell?

    <p>It can increase the number of electrons that can flow, thus increasing the current</p> Signup and view all the answers

    Which of the following best explains the concept of electromotive force (emf)?

    <p>The potential difference that drives electrons through the circuit</p> Signup and view all the answers

    Which of the following units is used to measure current in an electrochemical cell?

    <p>Ampere</p> Signup and view all the answers

    Which describes a spontaneous redox reaction in an electrochemical cell?

    <p>One that occurs naturally under standard conditions</p> Signup and view all the answers

    What determines the current flow through an electrochemical cell?

    <p>The voltage difference and the electrode surface area</p> Signup and view all the answers

    What occurs during the oxidation process of an element?

    <p>The element loses electrons</p> Signup and view all the answers

    Which condition is necessary for a reaction to be classified as a spontaneous redox reaction?

    <p>The reaction’s ΔG is negative</p> Signup and view all the answers

    In a voltaic (galvanic) cell, how is electric current generated?

    <p>By the flow of electrons from the anode to the cathode</p> Signup and view all the answers

    Which statement accurately describes reduction during a redox reaction?

    <p>Reduction occurs when electrons are added to an atom or compound</p> Signup and view all the answers

    An electrochemical cell functions primarily to convert which types of energy?

    <p>Chemical energy to electrical energy and vice versa</p> Signup and view all the answers

    What defines the flow of electrons in a spontaneous redox reaction within a voltaic cell?

    <p>Electrons flow from anode to cathode</p> Signup and view all the answers

    Which of the following components is essential for the operation of an electrolytic cell?

    <p>An external source of electrical energy</p> Signup and view all the answers

    During the half-reaction $ ext{Ag}^+ + e^- ightarrow ext{Ag(s)}$, what process is occurring?

    <p>Reduction of silver ions</p> Signup and view all the answers

    Study Notes

    Electrochemical Cells

    • Oxidation and reduction half-reactions occur in separate half-cells within electrochemical cells.
    • A complete electrical circuit requires electron flow through a wire and ions flowing via a salt bridge.
    • Conductive solid electrodes (metal or graphite) enable electron transfer through an external circuit.
    • The salt bridge facilitates ion exchange between half-cells and maintains charge balance.

    Voltage and Current

    • Voltage (measured in volts) is the potential energy difference between reactants and products.
    • Current (measured in amperes) indicates the number of electrons flowing per second.
    • 1 ampere equals 1 coulomb of charge flowing each second.
    • Voltage can be expressed as 1 V = 1 J of energy per coulomb.
    • 1 ampere corresponds to approximately 6.242 × 10^18 electrons per second.
    • Electrode surface area directly influences the current produced.

    Cell Potential

    • Cell potential refers to the difference in potential energy between the anode and cathode in a voltaic cell.
    • The effectiveness of the oxidizing agent at the cathode and the reducing agent at the anode influences cell potential.
    • The anode oxidizes, replacing metal cations in the solution.

    Mixtures of Ions and Electrolysis

    • When multiple cations are present, the one easiest to reduce, characterized by the least negative or most positive E°red, will be reduced first at the cathode.
    • When multiple anions are present, the one easiest to oxidize (least negative or most positive E°ox) will be oxidized first at the anode.

    Stoichiometry of Electrolysis

    • Product formation in an electrolytic cell correlates with the number of electrons transferred, treating electrons as reactants.
    • The flow of electrons depends on current and duration of the process; 1 amp equals 1 coulomb of charge per second.
    • One mole of electrons equals 96,485 coulombs of charge (Faraday's constant).
    • Calculation process: time (seconds) → coulombs → moles of electrons → moles of metal → grams of metal.

    Electrochemistry Overview

    • Electrochemistry studies redox reactions that generate or use electric current.
    • Electrochemical cells convert chemical energy to electrical energy, with spontaneous redox reactions occurring in galvanic/voltaic cells.
    • Nonspontaneous redox reactions require electrical energy input in electrolytic cells.

    Oxidation-Reduction Reactions

    • Redox reactions involve electron transfer where oxidation refers to loss of electrons and reduction refers to gain of electrons.
    • Oxidation characteristics include an increase in oxidation number or loss of hydrogen/oxygen.
    • Reduction characteristics include a decrease in oxidation number or gain of hydrogen/oxygen.

    Spontaneous Redox Reactions

    • Example of spontaneous reaction: Zn(s) + Cu²⁺(aq) → Zn²⁺ + Cu(s).
    • Voltaic (galvanic) cells harness electrical current from spontaneous redox reactions, which do not need external energy and have a negative ΔG.

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    Related Documents

    Chapter 17_Full chapter notes.pdf

    Description

    Test your understanding of electrochemical cells, specifically the processes of oxidation and reduction occurring in half-cells. This quiz covers the essential concepts related to electron flow, conductive electrodes, and the role of a salt bridge in creating an electrical circuit.

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