4.3.5 Representation of reactions at electrodes as half equations

• Oxidation in electrolysis occurs at the anode


  True
• Oxidation involves the loss of electrons
• Steps for writing half equations in electrolysis

  1️⃣ Balance the chemical equation

  2️⃣ Identify oxidation numbers

  3️⃣ Write oxidation and reduction half equations
• What is oxidation in terms of electron transfer?

  Loss of electrons
• What happens to copper ions at the cathode in the reduction half equation?

  They gain electrons
• Oxidation numbers decrease during reduction.

  False
• What is the balanced reduction half equation for silver ions (Ag⁺) to solid silver (Ag)?

  Ag⁺(aq) + e⁻ → Ag(s)
• A half equation can represent either oxidation or reduction
• A half equation represents the reactions happening at each electrode during electrolysis
• What is the key process at the anode in electrolysis?

  Oxidation
• What is the half equation for oxidation in the electrolysis of copper sulfate?

  Cu(s) → Cu²⁺(aq) + 2e^-
• Electron transfer is illustrated in half equations


  True
• In the oxidation half equation of copper, electrons are shown as being lost.


  True
• Steps for writing half equations in electrolysis

  1️⃣ Start with the balanced chemical equation

  2️⃣ Identify oxidation and reduction

  3️⃣ Write the oxidation half equation at the anode

  4️⃣ Write the reduction half equation at the cathode

  5️⃣ Show the transfer of electrons
• Balancing half equations with charge involves adding electrons
• In the electrolysis of copper sulfate, which half equation occurs at the cathode?

  Cu²⁺(aq) + 2e^- → Cu(s)
• Oxidation occurs at the anode during electrolysis.


  True
• Oxidation numbers increase during oxidation.


  True
• Steps for balancing half equations with charge and mass

  1️⃣ Identify the species undergoing oxidation or reduction

  2️⃣ Balance atoms of the element changing

  3️⃣ Balance charge by adding electrons

  4️⃣ Check mass and charge balance
• A half equation can represent the electron transfer during electrolysis
• Oxidation occurs at the anode, and reduction occurs at the cathode in electrolysis.


  True
• Combining half equations for oxidation and reduction results in the overall balanced equation for electrolysis.


  True
• Steps to combine half equations to form a balanced electrolysis equation:

  1️⃣ Write the oxidation half equation

  2️⃣ Write the reduction half equation

  3️⃣ Balance the number of electrons

  4️⃣ Add the two half equations
• Reduction in electrolysis occurs at the cathode
• Reduction involves the gain of electrons

  True
• What is the half equation for reduction in the electrolysis of copper sulfate?

  Cu²⁺(aq) + 2e^- → Cu(s)
• In a half equation, electron transfer is shown for the oxidation reaction at the anode
• The electron transfer in half equations demonstrates the process occurring during electrolysis
• Match the electrode with its half equation in the electrolysis of copper sulfate:

  Anode (Oxidation) ↔️ Cu(s) → Cu²⁺(aq) + 2e^-

  Cathode (Reduction) ↔️ Cu²⁺(aq) + 2e^- → Cu(s)
• A half equation focuses on the reaction at a single electrode during electrolysis.


  True
• Match the process with its location and reaction in electrolysis:

  Oxidation ↔️ Anode: Loss of electrons

  Reduction ↔️ Cathode: Gain of electrons
• The first step in writing half equations is to start with the balanced chemical equation
• Match the electrode with its half equation in the electrolysis of copper sulfate:

  Anode (Oxidation) ↔️ Cu(s) → Cu²⁺(aq) + 2e^-

  Cathode (Reduction) ↔️ Cu²⁺(aq) + 2e^- → Cu(s)
• What is the balanced reduction half equation for silver ions (Ag⁺) to solid silver (Ag)?

  Ag⁺(aq) + e⁻ → Ag(s)
• Charge is balanced in a half equation by adding electrons
• Match the process with its location in electrolysis:

  Oxidation ↔️ Anode

  Reduction ↔️ Cathode
• When combining half equations, the number of electrons lost must equal the number of electrons gained
• In the electrolysis of copper sulfate, solid copper is produced at the cathode.

  True
• What is the reduction half equation in the electrolysis of copper sulfate at the cathode?

  Cu²⁺(aq) + 2e^- → Cu(s)
• What must a half equation show to illustrate electron transfer accurately?

  The gain or loss of electrons