Electrode potentials and electrochemical cells (A-level only) exam tips

Exam tips

• Memorize key values

  Ensure you remember that the standard electrode potential of the SHE is 0.00 V.

  This value is fundamental for solving problems related to electrochemical cells and comparing other half-cell potentials.

• Always state the conditions for standard electrode potentials

  When defining or using standard electrode potentials, always mention the standard conditions (1 M, 1 atm, 25°C).

  This ensures clarity and precision in your answers, which is crucial for gaining full marks.

• Always check the signs of electrode potentials

  When calculating E°cell, ensure you correctly identify the cathode and anode based on their standard electrode potentials.

  Misidentifying these can lead to incorrect calculations of cell potential, impacting your overall answer.

• Draw clear electrochemical cell diagrams

  When drawing electrochemical cell diagrams, ensure to label the anode, cathode, and the direction of electron flow.

  Clear diagrams help in visualizing the cell setup and understanding the flow of electrons, which is crucial for answering related questions.

• Show All Working in Calculations

  Always show your calculations step-by-step, including units and final answers.

  This helps to avoid careless mistakes and allows for partial credit if the final answer is incorrect.

• Always check your electrode potentials

  Ensure you are using the correct signs for electrode potentials when calculating E°cell.

  Mistakes in sign can lead to incorrect conclusions about the feasibility of the reaction.

• Always Check Conditions

  When predicting the feasibility of a reaction, always check if the conditions are standard or non-standard.

  Standard electrode potentials are only valid under standard conditions; deviations can lead to incorrect predictions.

• Understand the differences

  Clearly differentiate between fuel cells, rechargeable batteries, and non-rechargeable batteries in your answers.

  This will help you accurately address comparison questions and demonstrate your understanding of their applications and impacts.

• Always show your calculations clearly

  When calculating cell potentials, clearly show each step of your calculation, including the use of the Nernst equation.

  This helps examiners follow your reasoning and ensures you receive credit for your method, even if the final answer is incorrect.