I- ,S2O8 2- and iron catalysis

• what does Fe2+ ions react with in I- and S2O8 2- reaction and what is produced?

  Reacts with : S2O8 2-

  products : 2SO4 2- and 2Fe3+
• what does Fe3+(aq) ions react with in I-(aq) and S2O8 2-(aq) reaction and what is produced (make sure its balanced) ?

  reacts with : 2I-(aq)

  produces : 2Fe2+(aq) and I2(aq)
• what features of iron makes it a good catalyst in the catalysis of I- and S2O8 2- to form SO4 2- and I2

  variable oxidation states

  positive charge (both reactants are negative so normally they would repel each other)
• what is I- oxidised by to form I2

  Fe3+