Calculate The Electrode Potential of The Following Half-Cells Io3

This calculator determines the electrode potential of the I₃^- half-cell using the Nernst equation. The Nernst equation relates the reduction potential of a half-cell to the activities of the species involved and the temperature.

Introduction

The electrode potential of a half-cell is a fundamental concept in electrochemistry. For the I₃^- half-cell, the reduction reaction is:

Reduction Reaction

I₃^- + 2e^- ⇌ 3I^-

The standard reduction potential (E⁰) for this reaction is 0.54 V. The Nernst equation allows us to calculate the actual electrode potential (E) when the activities of the species are known.

Nernst Equation Formula

Nernst Equation

E = E⁰ - (RT/nF) * ln(Q)

Where:

E = Electrode potential (V)
E⁰ = Standard reduction potential (V)
R = Gas constant (8.314 J/mol·K)
T = Temperature (K)
n = Number of electrons transferred
F = Faraday constant (96,485 C/mol)
Q = Reaction quotient (activity of products / activity of reactants)

The Nernst equation shows that the electrode potential depends on the activities of the species involved and the temperature. At standard conditions (25°C), the equation simplifies to:

Simplified Nernst Equation

E = E⁰ - (0.0592/n) * log(Q)

Worked Example

Let's calculate the electrode potential for the I₃^- half-cell with the following conditions:

Standard reduction potential (E⁰) = 0.54 V
Activity of I₃^- = 0.1 M
Activity of I^- = 0.01 M
Temperature = 25°C (298.15 K)

The reaction quotient (Q) is calculated as:

Reaction Quotient

Q = [I^-]³ / [I₃^-]

Q = (0.01)³ / 0.1 = 0.000001 / 0.1 = 0.00001

Using the simplified Nernst equation:

Electrode Potential Calculation

E = E⁰ - (0.0592/n) * log(Q)

E = 0.54 - (0.0592/2) * log(0.00001)

E = 0.54 - 0.0296 * (-5)

E = 0.54 + 0.148 = 0.688 V

The calculated electrode potential is 0.688 V.

Frequently Asked Questions

What is the Nernst equation used for?: The Nernst equation calculates the actual electrode potential of a half-cell reaction based on the activities of the species involved and the temperature.
What is the standard reduction potential for I₃^-?: The standard reduction potential for I₃^- is 0.54 V.
How does temperature affect electrode potential?: The Nernst equation shows that electrode potential depends on temperature through the RT term. Higher temperatures increase the electrode potential.
What is the reaction quotient (Q)?: The reaction quotient is the ratio of the activities of the products to the activities of the reactants in the half-cell reaction.