Electrolysis

• What is electrolysis?

  Electrolysis is the breaking down of a substance using electricity.
• What role does an electrolyte play in electrolysis?

  An electrolyte is a molten or dissolved ionic compound that decomposes when an electric current is passed through it.
• What occurs during oxidation in electrolysis?

  Oxidation involves the loss of electrons.
• What occurs during reduction in electrolysis?

  Reduction involves the gain of electrons.
• Where do positive ions move during electrolysis?

  Positive ions (cations) move towards the cathode (negative electrode).
• Where do negative ions move during electrolysis?

  Negative ions (anions) move towards the anode (positive electrode).
• What happens to ions as they gain or lose electrons during electrolysis?

  As ions gain or lose electrons, they form unchanged substances and are discharged from the electrolyte.
• What are the steps to write a half equation in electrolysis?

  1. Put one of the substances being oxidised or reduced on one side of an arrow and the product on the other.
  2. Balance the number of atoms like in a normal equation.
  3. Add electrons to one side to balance the charges.
• What is the half equation for sodium losing one electron to become a sodium ion?

  $Na \rightarrow Na^+$$+$$e^-$
• What is the half equation for hydrogen ions gaining electrons to become hydrogen gas?

  $2H^+$$+$$2e^- \rightarrow H_2$
• What components make up an electrochemical cell?

  • Anode
  • Cathode
  • Electrolyte
  • Power source
  • Wires connecting the electrodes
• What is the method to set up an electrochemical cell with a solution electrolyte?

  1. Use unreactive electrodes (e.g., graphite or platinum).
  2. Clean the electrodes' surfaces.
  3. Place electrodes in the solution.
  4. Connect to a power supply.
  5. Turn on the power supply to allow current flow.
• What is the method to set up an electrochemical cell with a molten ionic substance?

  1. Place the solid ionic substance in a crucible.
  2. Heat the crucible until the solid melts.
  3. Insert clean electrodes into the molten electrolyte.
  4. Connect the electrodes to a power supply.
  5. Turn on the power supply to allow current flow.
• Why can molten ionic solids be electrolysed?

  Molten ionic solids can be electrolysed because the ions can move freely and conduct electricity.
• What happens to metals during electrolysis at the cathode?

  Metals are reduced to metal atoms at the cathode.
• What happens to halide ions at the anode during electrolysis?

  Halide ions are oxidised to form molecules at the anode.
• What is produced at the cathode when sodium chloride solution is electrolysed?

  Hydrogen gas is produced at the cathode.
• What is produced at the anode when sodium chloride solution is electrolysed?

  Chlorine gas is produced at the anode.
• How does the reactivity of metals affect the products of electrolysis in aqueous solutions?

  If the metal is more reactive than hydrogen, hydrogen gas is produced; if less reactive, the pure metal is produced.
• What ions are present in a solution of sodium chloride (NaCl)?

  • Sodium ions (Na^+)
  • Chloride ions (Cl^-)
  • Hydroxide ions (OH^-)
  • Hydrogen ions (H^+)
• What is the half equation for the production of chlorine gas at the anode during electrolysis of sodium chloride solution?

  $2Cl^- \rightarrow Cl_2 +$$2e^-$
• What is the half equation for the production of hydrogen gas at the cathode during electrolysis of sodium chloride solution?

  $2H^+$$+$$2e^- \rightarrow H_2$
• What is the significance of the reactivity series in electrolysis?

  • Helps predict products of electrolysis.
  • Determines whether hydrogen or the metal is produced at the cathode.
  • Indicates which halogen will be produced at the anode.