4.3.4 Electrolysis of aqueous solutions

• What is the definition of electrolysis?

  Using electricity to break down compounds
• Which state of an electrolyte has high electrical conductivity?

  Molten or aqueous
• Why is an electrolyte necessary for electrolysis?

  To conduct electricity
• The anode and cathode are connected to a power supply
• What are the two electrodes in an electrolytic cell?

  Anode and cathode
• The most reactive ions are discharged first during electrolysis.


  True
• What is the process called that uses electricity to break down compounds into their constituent elements or ions?

  Electrolysis
• The electrolyte in an electrolytic cell contains ions that can move and conduct electricity
• Electrolysis can occur only when a substance is in a molten state.

  False
• The anode is the electrode where reduction occurs.

  False
• Molten sodium chloride has high electrical conductivity.


  True
• What is the process that occurs at the anode during electrolysis?

  Oxidation
• What is an example of an electrolyte in a molten state?

  Sodium chloride
• Which electrode in an electrolytic cell is where oxidation occurs?

  Anode
• What happens to positively charged ions at the anode during electrolysis?

  They lose electrons
• Match the type of electrolyte with its characteristic reaction at the anode:

  Aqueous ↔️ Water molecules are oxidized

  Molten ↔️ Desired ions are discharged
• In an aqueous NaCl solution, why is hydrogen gas produced at the cathode instead of sodium?

  Hydrogen is less reactive
• What effect does higher voltage have on ion discharge?

  Discharges less reactive ions
• Ionic equations for electrolytic reactions indicate the number of electrons transferred
• Ionic equations help understand how electrolysis breaks down compounds into their constituent elements.

  True
• Which gas is produced at the cathode in an aqueous NaCl solution due to the lower reactivity of H⁺ ions compared to Na⁺?

  Hydrogen gas
• Ions in the electrolyte must move freely to conduct electricity.

  True
• Negatively charged ions are attracted to the anode during electrolysis.

  False
• What is the main difference between molten electrolytes and aqueous electrolytes in electrolysis?

  No competition from water
• What effect does higher concentration have on ion discharge during electrolysis?

  Faster discharge
• Ionic equations for electrolytic reactions show the number of electrons transferred.


  True
• Match the electrolyte with its anode and cathode reactions:

  Molten NaCl ↔️ 2Cl⁻ → Cl₂ + 2e⁻ at anode, Na⁺ + e⁻ → Na at cathode

  Aqueous CuSO₄ ↔️ 2H₂O → O₂ + 4H⁺ + 4e⁻ at anode, Cu²⁺ + 2e⁻ → Cu at cathode
• A higher applied voltage can force less reactive ions to discharge
• At the cathode, negatively charged ions gain electrons during electrolysis.


  True
• What gas is often produced at the cathode in aqueous electrolysis due to the reduction of water?

  Hydrogen
• The cathode reaction in molten NaCl is Na⁺ + e⁻ → Na
• In an aqueous NaCl solution, hydrogen ions are more reactive than sodium ions.

  False
• Match the electrolyte with its anode and cathode reactions:

  Molten NaCl ↔️ 2Cl⁻ → Cl₂ + 2e⁻ (anode), Na⁺ + e⁻ → Na (cathode)

  Aqueous CuSO₄ ↔️ 2H₂O → O₂ + 4H⁺ + 4e⁻ (anode), Cu²⁺ + 2e⁻ → Cu (cathode)
• The three main factors influencing ion discharge during electrolysis are reactivity, concentration, and applied voltage
• Electrolysis occurs when an electric current passes through an electrolyte
• In an electrolytic cell, oxidation occurs at the anode
• During electrolysis, positively charged ions lose electrons at the anode
• The reactivity and concentration of ions in the electrolyte influence which ions are discharged at the anode
• Higher applied voltage can force less reactive ions to discharge
• What is the anode reaction in the electrolysis of molten NaCl?

  2Cl⁻ → Cl₂ + 2e⁻