8

• What must a half cell contain?

  An element in 2 oxidation states
• What are the definitions of oxidation and reduction?

  • Oxidation: loss of electrons
  • Reduction: gain of electrons
• Why must metal electrodes be cleaned with sandpaper before creating an electrochemical cell?

  To remove metal oxide and improve conductivity
• Describe the movement of electrons in an electrochemical cell.

  Electrons flow from positive to negative electrode
• What is the role of potassium nitrate solution in a standard Zn/Zn2+ cell?

  It saturates filter paper for the salt bridge
• Why is a salt bridge used in an electrochemical cell?

  To maintain charge balance and complete the circuit
• Why must an inert salt be used in the salt bridge?

  To prevent reaction with solutions and concentration changes
• What moves across the salt bridge?

  Ions
• In an electrochemical cell, what is each metal electrode placed in?

  A solution containing its ions
• What are the standard conditions for investigating electrochemical cells?

  • 1 mol dm^-3 solutions
  • 298 K
  • 1 atm
• What should be done if the voltmeter reading is negative after setting up an electrochemical cell?

  Switch the connection of the wires
• What is the formula for the electromotive force (EMF)?

  EMF = ER − EL
• For a reaction to be thermodynamically feasible, what must the value of the EMF be?

  Positive