CELLS

• WHERE DO ELECTRONS FLOW IN A CELL?

  from a more reactive metal to a less reactive one via a conducting wire
• WHAT IS A HALF CELL?

  when a rod of metal is dipped into a solution of its own ions creating an equilibrium

  e.g. Zn (s) ⇋ Zn (2+) (aq) + 2e-
• WHAT IS AN ELECTRICAL CELL USED FOR?

  to measure the reducing agent ability of a metal by measuring potential difference
• WHAT ARE THE FEATURES OF AN ELECTRICAL CELL?

  • high-resistance voltmeter
  • salt bridge
  • conducting wires
  • standard conditions
• WHAT ARE STANDARD CONDITIONS?

  100 kPa, 1 mol^dm-3, 298K, zero current
• HOW TO MAKE A SALT BRIDGE?

  • filter paper
  • soaked in a solution of potassium chloride/ nitrate
  • dissolved in agar gel
  • set in a U-tube
• WHAT TO CONSIDER WHEN MAKING A SALT BRDIGE?

  do not use potassium chloride for copper as [CuCl4]2- complexes are formed
• WHAT IS A HYDROGEN ELECTRODE USED FOR?

  compare tendency of different metals to act as a reducing agent at standard conditions
• WHAT DOES A HYDROGEN ELECTRODE CONSIST OF?

  • platinum wire
  • glass bell
  • platinum metal
  • H+ solution
  • H2 gas