redox + galvanic cells

• what is an electrochemical cell?

  a device in which chemical energy is converted into electrical energy or vice versa
• what is a galvanic cell?

  • also known as a voltaic cell
  • type of electrochemical cell where chemical energy is converted into electrical energy
  • use in mobile phones + laptops
  • consists of two half-cells (each half cell contains an electrode in contact with a solution)
• what is a battery?

  • a combination of cells
• what is the external circuit of a daniell cell?


  wires + voltmeter
• what is the internal circuit of a daniell cell?

  salt bridge
• what is an electrolyte?

  a chemical subtance that conducts electric current
• when electrons are accepted by ions, a deposit is formed on the electrode

  e.g. Cu2+(aq) + 2e- -> Cu(s)
• what is a spontaneous reaction?

  • a reaction that does not need to be driven by an external source of energy
• what is an oxidising agent?


  a chemical that causes another substance to be oxidised (aka oxidant)
• what is a reducing agent?


  a chemical that causes another substance to be reduced (aka reductant)
• what are the two basic types of galvanic cells?

  • primary cells
  • secondary cells
• what is a primary cell?

  • disposable
  • designed not to be recharged
  • often referred to as non-rechargeable cells
  • 'go flat' when the cell reaction reaches equilibrium (when there is no tendency for the quantities of reactants and products to change)
• what is a secondary cell?

  • rechargeable cells
  • designed to be reused many times
• what prevents primary cells from being recharged?

  in primary cells, the products slowly migrate away from the electrodes or are consumed by side reactions occurring in the cell
• what are the pros of primary cells?

  • a type of primary cell called an alkaline cell is especially cost-effective in torches and motorised toys, where currents are needed intermittently