C4b

• What is the process used to extract metals from molten or dissolved compounds?

  Electrolysis
• Why is electrolysis used for extracting aluminium?

  Because aluminium is more reactive than carbon
• What is a disadvantage of electrolysis for metal extraction?

  It requires a lot of electrical energy
• What type of current is used in electrolysis?

  Direct current
• What is the positive electrode called in electrolysis?

  Anode
• What is the negative electrode called in electrolysis?

  Cathode
• What happens to positive ions during electrolysis?

  They move to the negative electrode
• What happens to negative ions during electrolysis?

  They move to the positive electrode
• What mnemonic helps remember the electrode charges?

  Don't P.A.N.I.C.
• What is mixed with aluminium oxide to reduce its melting point?

  Cryolite
• What is the reaction for the extraction of aluminium from aluminium oxide?

  $2Al_2O_3 (l) \rightarrow 4Al (l) +$$3O_2 (g)$
• What occurs at the cathode during aluminium extraction?

  $Al^{3+} +$$3e^- \rightarrow Al$
• What occurs at the anode during aluminium extraction?

  $2O^{2-} \rightarrow O_2 (g) +$$4e^-$
• What does OIL RIG stand for in electrolysis?

  Oxidation Is Loss, Reduction Is Gain
• What happens to the carbon electrodes during electrolysis?

  They react to produce carbon dioxide
• What is the reaction for carbon reacting with oxygen during electrolysis?

  $C (s) +$$O_2 (g) \rightarrow CO_2 (g)$
• What happens to water during electrolysis in an aqueous solution?

  It dissociates into H+ and OH- ions
• What is produced at the negative electrode if the metal is less reactive than hydrogen?

  The metal will be produced
• What is produced at the negative electrode if the metal is more reactive than hydrogen?

  Hydrogen will be produced
• What is formed at the positive electrode if halide ions are present?

  Chlorine, bromine, or iodine
• What is formed at the positive electrode if no halide ions are present?

  Oxygen from hydroxide ions
• What are the products of the electrolysis of brine?

  H2, Cl2, and NaOH
• What is the reaction at the positive electrode during the electrolysis of brine?

  $2Cl^{-} \rightarrow Cl_2 (g) +$$2e^{-}$
• What is the reaction at the negative electrode during the electrolysis of brine?

  $2H^{+} +$$2e^{-} \rightarrow H_2 (g)$
• What is the reaction in solution during the electrolysis of brine?

  $Na^{+} +$$OH^{-} \rightarrow NaOH$
• What is produced in sodium chloride solution during electrolysis?

  Sodium hydroxide solution
• What are the steps involved in the electrolysis of aluminium oxide?

  • Aluminium oxide is mixed with cryolite
  • Electrolysis occurs to produce aluminium and oxygen
  • Aluminium forms at the cathode
  • Oxygen forms at the anode
• What are the key concepts of electrolysis in solutions?

  • Ions become free to move in solution
  • Positive ions move to the cathode
  • Negative ions move to the anode
  • Products depend on the reactivity of the metal and presence of halide ions
• What are the differences in products at the electrodes based on metal reactivity during electrolysis?

  • Less reactive metal: metal produced at cathode
  • More reactive metal: hydrogen produced at cathode
  • Halide ions: halogen produced at anode
  • No halide ions: oxygen produced at anode