Page 3: Understanding Electrode Potentials

This page focuses on the interpretation of electrode potentials and their relationship to the reactivity of elements in electrochemical cells. It provides crucial information for students studying electrode potentials in A-Level Chemistry.

Definition: The electrode potential is a measure of the tendency of a species to undergo oxidation or reduction.

Key points about electrode potentials:

• Negative electrode potential indicates a strong reducing agent (easily oxidized)
• Positive electrode potential indicates a strong oxidizing agent (easily reduced)

Example: In the zinc-copper cell:

• Zn²⁺/Zn has an electrode potential of -0.76 V (reducing agent, more reactive)
• Cu²⁺/Cu has an electrode potential of +0.34 V (oxidizing agent, less reactive)

The page also provides guidance on drawing electrochemical cells:

• Place the more negative (more reactive) electrode on the left-hand side
• Show the direction of electron flow in the external circuit
• Indicate the salt bridge connecting the two half-cells

Highlight: Understanding how to draw and interpret electrochemical cell diagrams is essential for solving electrode potential A-level Chemistry questions.

Page 5: Standard Hydrogen Electrode and Cell Notation

This page introduces the concept of the Standard Hydrogen Electrode (SHE) and explains cell notation, both crucial topics for understanding electrode potentials in A-Level Chemistry.

Definition: The Standard Hydrogen Electrode (SHE) is a primary reference electrode used to measure the standard electrode potentials of other half-cells.

Components of the Standard Hydrogen Electrode:

• Platinum electrode
• Hydrogen gas at 100 kPa (1 atm) pressure
• 1.0 M H⁺(aq) solution
• Temperature maintained at 298 K (25°C)

Highlight: The SHE is assigned a standard potential of 0.00 V, serving as the reference point for all other electrode potentials.

The page also explains cell notation, a shorthand method for representing electrochemical cells:

• Format: Reduced form | Oxidized form || Oxidized form | Reduced form
• Example: Pt(s) | H₂(g) | H⁺(aq) || Cu²⁺(aq) | Cu(s)

Vocabulary: Phase boundary - The interface between two different phases in an electrochemical cell, such as solid-liquid or gas-liquid interfaces.

Example: In a cell combining the SHE with a copper electrode: Left half-cell: Pt(s) | H₂(g) | H⁺(aq) Right half-cell: Cu²⁺(aq) | Cu(s) Cell notation: Pt(s) | H₂(g) | H⁺(aq) || Cu²⁺(aq) | Cu(s)

Understanding the SHE and cell notation is essential for students working on setting up electrochemical cells with salt bridge lab reports and solving complex electrochemistry problems.

Page 1: Introduction to Electrochemical Cells

This page introduces the fundamental concepts of electrochemical cells and their components. Electrochemical cells are devices that convert chemical energy into electrical energy through redox reactions. They consist of two half-cells connected by a salt bridge and an external circuit.

Definition: An electrochemical cell is a system composed of two half-cells that undergo redox reactions to generate an electric current.

The key components of an electrochemical cell include:

1. Two different metals dipped in solutions of their own ions
2. A wire connecting the metals to form an external circuit
3. A salt bridge connecting the two solutions

Highlight: The salt bridge is crucial for maintaining electrical neutrality in the cell by allowing ion flow between half-cells.

The page also explains the process of setting up an electrochemical cell:

1. Connect the two metals with a wire for electron flow
2. Join the solutions with a salt bridge for ion flow
3. Use a voltmeter in the circuit to measure the potential difference (emf)

Example: In a copper-zinc cell, zinc loses electrons more easily than copper, making it the anode where oxidation occurs. Electrons flow through the external circuit from zinc to copper, while the salt bridge allows ions to flow between half-cells to balance charges.

Vocabulary: EMF (electromotive force) - The potential difference between the two electrodes in an electrochemical cell.