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Electrochemistry in General Chemistry

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  • What defines a redox reaction?
    A redox reaction involves the transfer of electrons between atoms, where oxidation is the loss of electrons and reduction is the gain of electrons.
  • What is the role of the reducing agent in a redox reaction?
    The reducing agent donates electrons and is itself oxidized during the reaction.
  • What is the role of the oxidizing agent in a redox reaction?
    The oxidizing agent accepts electrons and is itself reduced during the reaction.
  • How do you balance redox reactions using the half-reaction method in acidic solution?
    Assign oxidation numbers, separate into half-reactions, balance elements except H and O, balance O with H2O, balance H with H+, balance charge with electrons, equalize electrons, then add and simplify.
  • What is the function of the salt bridge in a voltaic cell?
    The salt bridge maintains electrical neutrality by allowing ion migration between half-cells, completing the circuit.
  • Where does oxidation occur in a voltaic cell?
    Oxidation occurs at the anode, which is the negative electrode in a voltaic cell.
  • Where does reduction occur in a voltaic cell?
    Reduction occurs at the cathode, which is the positive electrode in a voltaic cell.
  • What is the standard hydrogen electrode (SHE) potential?
    The SHE is the reference electrode with a defined standard reduction potential of 0 V under standard conditions.
  • How is the standard cell potential (E°cell) calculated?
    E°cell = E°cathode - E°anode, the difference between cathode and anode standard reduction potentials.
  • What does a positive E°cell indicate about a reaction?
    A positive E°cell indicates a spontaneous redox reaction under standard conditions.
  • What is the relationship between Gibbs free energy change (ΔG°) and cell potential?
    ΔG° = -nFE°cell, where n is moles of electrons and F is Faraday's constant; negative ΔG° means spontaneous reaction.
  • What is the Nernst equation for cell potential at nonstandard conditions?
    Ecell = E°cell - (0.0592/n) log Q, where Q is the reaction quotient and n is number of electrons transferred.
  • What is a concentration cell?
    A concentration cell has identical electrodes but different ion concentrations, causing electron flow due to concentration gradient.
  • What is the main difference between voltaic and electrolytic cells?
    Voltaic cells generate electrical energy from spontaneous reactions; electrolytic cells use electrical energy to drive nonspontaneous reactions.
  • In electrolysis, which electrode is positive and which is negative?
    The anode is positive (oxidation occurs), and the cathode is negative (reduction occurs) in electrolytic cells.
  • What is electroplating?
    Electroplating uses electrolysis to deposit a metal coating on a cathode workpiece by reducing metal cations onto its surface.
  • How is the amount of substance produced in electrolysis calculated?
    Use current and time to find coulombs, convert to moles of electrons, then use stoichiometry to find moles of substance plated or produced.
  • What is a sacrificial electrode in corrosion prevention?
    A more reactive metal attached to a metal protects it by corroding first, acting as a sacrificial anode.
  • What is the activity series in electrochemistry?
    A list of metals ranked by their tendency to be oxidized; metals above H2 dissolve in acids, those below do not.
  • What is the electromotive force (emf) in an electrochemical cell?
    The emf is the voltage or driving force pushing electrons through the external circuit.