Electrochemistry Lab - Week 2 Overview

Electrochemistry Lab - Week 2

• Voltaic Cell: Previous week focused on Voltaic cells. This week focuses on concentration cells.

• Voltaic Cell Review:

  • Standard electrode potentials:

  • E°red = -0.76 V

  • E°ox = +0.76 V

  • E°cell = E°ox + E°red = 1.10 V

  • Half-reactions:

  • Cu → Cu²⁺ (1M) + 2e⁻

  • Cu²⁺ (1M) + 2e⁻ → Cu

• Nonstandard Conditions:

  • Example changes in concentrations:

  • Cu → Cu²⁺ (0.010 M) + 2e⁻

  • Cu²⁺ (2.0M) + 2e⁻ → Cu

• Concentration Cell:

  • Definition: A concentration cell is a type of voltaic cell with the same metal in both electrodes but different ion concentrations.

  • Characteristics:

  • Driving force: difference in ion concentration.

  • Electrons flow from anode (dilute side) to cathode (concentrated side).

  • E°cell = 0 V, but Ecell ≠ 0 due to concentration gradient.

  • Generates electricity spontaneously.

• Nernst Equation: Used to calculate cell potential based on concentration differences in half-cells.

• Reaction Quotient (Q):

  • Formula: Q = \frac{[\text{products}]}{[\text{reactants}]}

  • Example context: concentrations in Cu cell.

• Lab Activity:

  • Creating concentration cells using different concentrations of copper ion solution.

• Serial Dilution Example:

  • Preparing concentrations:

  • 1 M stock solution

  • Sequence of dilutions:

    • 0.1 M, 0.01 M, 0.001 M (using 9 mL diluent for each dilution step).

This week’s lab focuses on concentration cells, which are a type of voltaic cell featuring the same metal in both electrodes but have different ion concentrations. The slides introduce standard electrode potentials, with examples of half-reaction changes illustrating nonstandard conditions. The driving force for concentration cells is the difference in ion concentration which allows electrons to flow from the anode to the cathode and generate electricity spontaneously. We use the Nernst Equation is to calculate cell potential based on differences in concentration and it shows that even though Ecell is 0 V, it still has potential because of the difference in ion.