# Galvanic Cell EMF Calculator

E⁰cell = E⁰cathode − E⁰anode with ΔG⁰, the spontaneity verdict, and log₁₀K at 25 °C.

> Canonical page: https://elysiatools.com/en/tools/galvanic-cell-emf

- **Category:** Science & Education

- **Keywords:** galvanic cell emf, standard cell potential, cathode anode, reduction potential, spontaneous reaction, electrochemistry

## Overview

The Galvanic Cell EMF Calculator computes the standard electromotive force (E⁰cell) of an electrochemical cell using standard reduction potentials for cathode and anode half-reactions. It instantly determines cell spontaneity, standard Gibbs free energy (ΔG⁰), and the equilibrium constant (K) at 25 °C based on the number of moles of electrons transferred.

## Inputs

- **Cathode potential E⁰ (V)** (number): e.g. 0.34 (Cu²⁺/Cu)
- **Anode potential E⁰ (V)** (number): e.g. -0.76 (Zn²⁺/Zn)
- **Electrons transferred n** (number): e.g. 2

## When to use

- Determining whether a redox reaction is spontaneous (galvanic) or non-spontaneous (electrolytic) under standard conditions.
- Calculating standard cell potential (E⁰cell) and corresponding Gibbs free energy (ΔG⁰) for electrochemistry homework and lab experiments.
- Evaluating the thermodynamic equilibrium constant (K or log₁₀K) for multi-electron electrochemical couples at 25 °C.

## How it works

- Enter the standard reduction potential of the cathode (E⁰cathode) in volts.
- Enter the standard reduction potential of the anode (E⁰anode) in volts.
- Specify the number of transferred electrons (n) involved in the balanced redox equation.
- Review the resulting E⁰cell, ΔG⁰ in kJ/mol, log₁₀K, absolute equilibrium constant K, and spontaneity verdict.

## Use cases

- Verifying electrochemical calculations for general and physical chemistry coursework.
- Predicting battery voltage and driving force for metal-ion redox pairs in laboratory setups.
- Checking thermodynamic feasibility and equilibrium extents for industrial redox systems.

## Frequently asked questions

### What formula calculates the standard cell EMF?

The calculator evaluates standard cell potential using E⁰cell = E⁰cathode − E⁰anode, where both potentials are standard reduction potentials.

### How is standard Gibbs free energy (ΔG⁰) determined?

It is calculated using ΔG⁰ = −nFE⁰cell, where n is the number of moles of electrons and F is Faraday's constant (96,485 C/mol).

### How is the equilibrium constant (K) calculated at 25 °C?

K is calculated using the Nernst relationship log₁₀K = (n × E⁰cell) / 0.0592 V at standard room temperature (298.15 K).

### What indicates whether a cell reaction is spontaneous?

A positive E⁰cell (and negative ΔG⁰) indicates a spontaneous galvanic cell; a negative E⁰cell indicates an electrolytic cell requiring external power.

### Do I need to reverse the sign of the anode potential before entering it?

No. Enter standard reduction potentials directly for both cathode and anode; the formula automatically accounts for the oxidation sign inversion.

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