Nernst Equation Calculator

Nernst Equation:

\[ E = E^\circ - \frac{RT}{nF} \ln Q \]

Standard Cell Potential (E°):

Gas Constant (R):

J/mol·K

Temperature (T):

Moles of Electrons (n):

mol

Faraday Constant (F):

C/mol

Reaction Quotient (Q):

unitless

Cell Potential (E):

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1. What is the Nernst Equation?

The Nernst equation calculates the cell potential of an electrochemical cell under non-standard conditions. It relates the measured cell potential to the standard cell potential and the reaction quotient, accounting for temperature and concentration effects.

2. How Does the Calculator Work?

The calculator uses the Nernst equation:

\[ E = E^\circ - \frac{RT}{nF} \ln Q \]

Where:

\( E \) — Cell potential (V)
\( E^\circ \) — Standard cell potential (V)
\( R \) — Gas constant (8.314 J/mol·K)
\( T \) — Temperature (K)
\( n \) — Moles of electrons transferred (mol)
\( F \) — Faraday constant (96485 C/mol)
\( Q \) — Reaction quotient (unitless)

Explanation: The equation shows how the cell potential changes with concentration and temperature, with the logarithmic term accounting for the reaction's departure from standard conditions.

3. Importance of Cell Potential Calculation

Details: Calculating cell potential is essential for understanding electrochemical systems, battery performance, corrosion processes, and predicting the spontaneity of redox reactions under various conditions.

4. Using the Calculator

Tips: Enter all required values with appropriate units. Standard values for R (8.314 J/mol·K) and F (96485 C/mol) are pre-filled. Temperature is typically 298.15 K for standard calculations.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the reaction quotient Q?
A: Q represents the ratio of product concentrations to reactant concentrations, each raised to the power of their stoichiometric coefficients.

Q2: When does the Nernst equation predict E = E°?
A: When Q = 1 (ln Q = 0), which occurs when all species are at standard concentrations (1 M for solutions, 1 atm for gases).

Q3: How does temperature affect cell potential?
A: The temperature appears in both the numerator and the logarithmic term, making the relationship complex. Generally, cell potential decreases with increasing temperature for spontaneous reactions.

Q4: What are common values for the Faraday constant?
A: The Faraday constant is approximately 96485 C/mol, representing the electric charge of one mole of electrons.

Q5: Can this equation be used for concentration cells?
A: Yes, the Nernst equation is particularly useful for concentration cells where E° = 0, and the potential arises solely from concentration differences.