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Potentiometry quiz

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  • What does potentiometry measure in an electrochemical cell?
    Potentiometry measures the voltage difference between two electrodes without current flow.
  • What is the main purpose of the reference electrode in potentiometry?
    The reference electrode maintains a constant potential and serves as a stable comparison for the indicator electrode.
  • How is the cell potential (Ecell) calculated in potentiometry?
    Ecell is calculated as the potential of the indicator electrode minus the potential of the reference electrode plus the junction potential.
  • What is the function of the indicator electrode in potentiometry?
    The indicator electrode interacts with the analyte and its potential changes based on the analyte's composition.
  • Why is potassium chloride commonly used in the salt bridge of potentiometric cells?
    Potassium chloride is used because its ions are similar in size, minimizing the junction potential.
  • What is the junction potential and how can it be minimized?
    The junction potential arises from ion imbalances at the salt bridge and can be minimized by using ions of similar size, like K+ and Cl-.
  • What does the Nernst equation relate in potentiometry?
    The Nernst equation relates the electrode potential to the concentrations of the reduced and oxidized forms of the analyte.
  • In a potentiometric cell, which electrode is typically the anode?
    The reference electrode is typically the anode in a potentiometric cell.
  • What happens at the cathode in the example given in the transcript?
    At the cathode, Fe3+ absorbs an electron to become Fe2+, and a platinum electrode is used as an inert electrode.
  • Why is the reference electrode's concentration held constant?
    The reference electrode's concentration is held constant to ensure its potential remains unchanged during measurements.
  • What is the role of the salt bridge in potentiometry?
    The salt bridge maintains electrical neutrality and minimizes the junction potential between the two half-cells.
  • How does potentiometry provide information about the analyte?
    By measuring the voltage difference, potentiometry reveals details about the analyte's composition and concentration.
  • What is formed when silver and chloride ions combine in the cell?
    A precipitate of silver chloride (AgCl) is formed when silver and chloride ions combine.
  • Why is a platinum electrode used in some potentiometric cells?
    A platinum electrode is used as an inert electrode when no solid metal is formed at the cathode.
  • What does a negative sign indicate in the cell notation for potentiometry?
    A negative sign indicates the anode side of the electrochemical cell.