Standard Cell Potential (EMF) Calculator
Calculate standard cell EMF as E_cathode − E_anode.
Formula first
Overview
The standard cell potential measures the maximum voltage difference between two electrodes under standard conditions, typically 1 M concentration, 1 atm pressure, and 25°C. It serves as the primary quantitative measure of the thermodynamic driving force for a redox reaction to occur spontaneously in an electrochemical cell.
Symbols
Variables
= Cathode Potential, = Anode Potential, = Cell Potential
Apply it well
When To Use
When to use: Use this equation when analyzing galvanic or electrolytic cells operating under standard state conditions. It is specifically applicable when given the standard reduction potentials for two half-reactions to determine which electrode will act as the cathode and which as the anode.
Why it matters: Calculating the cell potential is essential for predicting if a chemical reaction can generate electricity or if it requires an external energy source to proceed. This calculation is the foundation for designing modern batteries, predicting corrosion in infrastructure, and optimizing industrial electrolysis processes.
Avoid these traps
Common Mistakes
- Reversing cathode and anode.
- Forgetting signs of half-cell potentials.
One free problem
Practice Problem
A Daniell cell is constructed using a zinc electrode in a Zn²⁺ solution and a copper electrode in a Cu²⁺ solution. If the standard reduction potential of copper (cathode) is +0.34 V and zinc (anode) is -0.76 V, calculate the standard cell potential.
Solve for:
Hint: Subtract the standard reduction potential of the anode from that of the cathode.
The full worked solution stays in the interactive walkthrough.
References
Sources
- Atkins' Physical Chemistry
- IUPAC Gold Book: Standard electrode potential
- Wikipedia: Standard electrode potential
- IUPAC Gold Book: 'Standard electrode potential'
- Wikipedia: 'Standard electrode potential'
- IUPAC Gold Book
- AQA A-Level Chemistry — Redox and Electrode Potentials