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Coulometry quiz

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  • What is the key difference between galvanic (voltaic) and electrolytic cells in terms of reaction spontaneity?
    Galvanic cells involve spontaneous reactions, while electrolytic cells involve non-spontaneous reactions that require external energy.
  • What does a negative Gibbs free energy (ΔG < 0) indicate about an electrochemical cell?
    It indicates the reaction is spontaneous and the cell is a galvanic (voltaic) cell.
  • What is the equilibrium constant (K) for a spontaneous reaction in an electrochemical cell?
    For a spontaneous reaction, K is greater than 1.
  • How does cell potential relate to spontaneity in electrochemical cells?
    A cell potential greater than 0 indicates a spontaneous reaction; less than 0 indicates a non-spontaneous reaction.
  • What is the sign of entropy change (ΔS) for a spontaneous electrochemical reaction?
    ΔS is greater than 0 for a spontaneous reaction.
  • What does it mean when the reaction quotient (Q) is less than the equilibrium constant (K)?
    It means the reaction will shift in the forward direction toward equilibrium.
  • What type of electrochemical cell is associated with a non-spontaneous reaction?
    A non-spontaneous reaction is associated with an electrolytic cell.
  • What external requirement is needed for an electrolytic cell to operate?
    An electrolytic cell requires an external energy source, such as a battery, to drive the reaction.
  • What happens to an electrochemical cell at equilibrium?
    At equilibrium, the cell represents a dead battery and has discharged all its electricity.
  • In an electrolytic cell, what is the charge of the anode and cathode?
    The anode is positive and the cathode is negative in an electrolytic cell.
  • Why do electrons require a battery to move in an electrolytic cell?
    Because electrons do not naturally move toward a negative cathode, a battery is needed to force the reaction.
  • What is always true about the reactions at the anode and cathode in both cell types?
    The anode always undergoes oxidation and the cathode always undergoes reduction.
  • How does the direction of electron flow differ between galvanic and electrolytic cells?
    In galvanic cells, electrons flow naturally from anode to cathode; in electrolytic cells, a battery forces electrons to flow from anode to cathode.
  • What is the relationship between Q and K in a non-spontaneous reaction?
    In a non-spontaneous reaction, Q is greater than K, causing the reaction to shift in the reverse direction.
  • What is the main function of a battery in an electrolytic cell?
    The battery provides the energy needed to drive a non-spontaneous reaction by forcing electron flow.