Standard Cell Potential Calculator
EMF from reduction potentials.
Formula first
Overview
The standard cell potential measures the electrical potential difference between two half-cells under standard conditions of 25°C, 1 M concentration, and 1 atm pressure. It determines the maximum voltage a galvanic cell can deliver and indicates whether a redox reaction will occur spontaneously.
Symbols
Variables
E_{cell}^\theta = Cell Potential, E_{red}^\theta = Cathode Potential, E_{ox}^\theta = Anode Potential
Apply it well
When To Use
When to use: Use this equation when calculating the electromotive force (EMF) of a voltaic or electrolytic cell under standard state conditions. It assumes that both the reduction and oxidation half-cell values are provided as standard reduction potentials.
Why it matters: This calculation is fundamental for designing batteries and fuel cells, as it predicts the energy output of chemical reactions. It also allows chemists to determine the spontaneity of reactions; a positive standard cell potential signifies a spontaneous process.
Avoid these traps
Common Mistakes
- Subtracting in wrong order.
- Changing sign of tabulated values.
One free problem
Practice Problem
A student constructs a silver-zinc cell. If the standard reduction potential of the silver cathode is 0.80 V and the standard reduction potential of the zinc anode is -0.76 V, calculate the standard cell potential.
Solve for:
Hint: Subtract the anode's reduction potential from the cathode's reduction potential.
The full worked solution stays in the interactive walkthrough.
References
Sources
- Atkins' Physical Chemistry
- Brown, LeMay, Bursten, Murphy, Woodward, Stoltzfus. Chemistry: The Central Science
- Wikipedia: Standard electrode potential
- IUPAC Gold Book
- NIST CODATA
- NIST Chemistry WebBook
- CRC Handbook of Chemistry and Physics
- Bard and Faulkner Electrochemical Methods: Fundamentals and Applications