Cell EMF Calculator
Calculate the electromotive force (EMF) of electrochemical cells using standard electrode potentials
Calculate Cell EMF
Standard reduction potential of the anode (negative electrode)
Standard reduction potential of the cathode (positive electrode)
Cell EMF Results
Formula: EMF = E°(cathode) - E°(anode)
Calculation: 0.000 V - (0.000 V) = 0.000 V
Analysis: The system is at equilibrium with no net reaction
Energy Flow: No net reaction
Example Electrochemical Cells
Daniell Cell
Classic zinc-copper galvanic cell
Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
Galvanic Cell
High voltage magnesium-silver cell
Mg(s) + 2Ag⁺(aq) → Mg²⁺(aq) + 2Ag(s)
Lead-Acid Battery
Common automotive battery system
Pb(s) + PbO₂(s) + 2H₂SO₄(aq) → 2PbSO₄(s) + 2H₂O(l)
Standard Electrode Potentials
Standard conditions: 25°C, 1 M concentration, 1 bar pressure
EMF Interpretation
EMF > 0 (Positive)
Spontaneous reaction
Galvanic/Voltaic cell
Generates electrical energy
EMF < 0 (Negative)
Non-spontaneous reaction
Electrolytic cell
Requires electrical energy input
EMF = 0
System at equilibrium
No net reaction
No current flow
Cell Components
Understanding Cell EMF and Electrochemistry
What is Electromotive Force (EMF)?
EMF is the maximum potential difference between the cathode and anode of an electrochemical cell when no current is flowing. It represents the cell's ability to drive an electric current through an external circuit and is measured in volts (V).
Key Concepts
- •Standard Conditions: 25°C, 1 M concentration, 1 bar pressure
- •Electrode Potential: Tendency of an electrode to gain or lose electrons
- •Galvanic Series: Arrangement of metals by their electrode potentials
EMF Calculation Formula
Basic Formula
EMF = E°(cathode) - E°(anode)
EMF = Electromotive force (V)
E°(cathode) = Standard reduction potential of cathode
E°(anode) = Standard reduction potential of anode
Remember
• Cathode has higher potential (more positive)
• Anode has lower potential (more negative)
• Positive EMF indicates spontaneous reaction
Applications of Electrochemical Cells
Batteries
Portable energy storage devices using galvanic cells for power generation.
Electroplating
Using electrolytic cells to deposit thin metal layers for protection or decoration.
Corrosion Protection
Understanding electrode potentials helps prevent metal corrosion through cathodic protection.
Daniell Cell Example
Cell Setup
Anode: Zn | Zn²⁺ (E° = -0.76 V)
Cathode: Cu²⁺ | Cu (E° = +0.34 V)
Overall Reaction: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
EMF Calculation
EMF = E°(Cu²⁺/Cu) - E°(Zn²⁺/Zn)
EMF = (+0.34 V) - (-0.76 V)
EMF = +1.10 V (Spontaneous)