Calculate E Cell for Following Equation Ph

Introduction

The standard electrode potential (E° cell) is a fundamental concept in electrochemistry that describes the potential difference between the oxidation and reduction half-reactions in a galvanic cell. When calculating E° cell for a given equation, you need to consider the standard electrode potentials of the individual half-reactions and adjust for the pH of the solution.

The Nernst equation allows you to calculate the actual cell potential (E cell) under non-standard conditions, taking into account the concentrations of the reactants and products. This calculator provides a straightforward way to compute E° cell for any given redox reaction.

Formula

The standard cell potential (E° cell) is calculated by subtracting the standard reduction potential of the oxidation half-reaction from the standard reduction potential of the reduction half-reaction.

Worked Example

Let's calculate the E° cell for the following redox reaction at 25°C (298 K):

Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)

Given:

• Standard reduction potential for Cu²⁺ + 2e^- → Cu(s): +0.34 V
• Standard reduction potential for Zn²⁺ + 2e^- → Zn(s): -0.76 V
• Number of electrons transferred (n): 2

The E° cell is calculated as:

E° cell = E°_red - E°_ox = 0.34 V - (-0.76 V) = 1.10 V

This means the standard cell potential for this reaction is 1.10 volts.

Interpreting Results

The calculated E° cell value indicates the maximum voltage that can be generated by the galvanic cell under standard conditions. A positive E° cell value indicates a spontaneous reaction, while a negative value indicates a non-spontaneous reaction.

When the pH of the solution is not 0, you need to adjust the standard reduction potentials of the half-reactions that involve hydrogen ions (H⁺). The adjustment is made using the following equation:

After adjusting the standard reduction potentials for the pH of the solution, you can calculate the E° cell using the standard method.