5.2.3 - Redox and Electrode Potentials

Question 1

oxidising agent

Answer 1

oxidises another species, is itself reduced (takes electrons)

Question 2

reducing agent

Answer 2

reduces another species, is itself oxidised (donates electrons)

Question 3

half-cell

Answer 3

• contains chemical species present in a redox half-equation
• voltaic (electrochemical) cell made by connecting 2 different half-cells
• allows electrons to flow

Question 4

metal/metal ion half-cells

Answer 4

• metal rod dipped in solution of its aqueous metal ion
• equilibrium set up
• forward reaction shows reduction and reverse reaction shows oxidation
• isolated half-cell: no net transfer of electrons into/out of metal
• connected half-cells: direction of electron flow depends on relative tendency of each electrode to release electrons

Question 5

ion/ion half-cells

Answer 5

• contains ions of same element in different oxidation states
• e.g. aqueous iron(II) and iron(III) ions
• no metal to transport electrons into/out of half-cell
• inert platinum metal electrode used

Question 6

standard electrode potential (E^⦵)

Answer 6

• the tendency to be reduced and gain electrons
• standard: half-cell containing H₂ gas and solution containing aqueous H⁺ ions
• inert platinum electrode used to allow electrons into/out of half-cell

Question 7

standard conditions

Answer 7

• solutions have concentration of exactly 1 mol dm^-3
• temperature is 298K (25°C)
• pressure is 100kPa (1 bar)