EMF of Cell Formula:
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Definition: This calculator determines the electromotive force (EMF) of a concentration cell where the two half-cells contain the same electrolyte but at different concentrations, without ion transference.
Purpose: It helps electrochemists and researchers understand the potential difference created by concentration gradients in electrochemical cells.
The calculator uses the Nernst equation for concentration cells:
Where:
Explanation: The formula accounts for the concentration difference and non-ideal behavior through activity coefficients.
Details: Accurate EMF calculation is crucial for understanding cell potentials, battery performance, and electrochemical reactions.
Tips: Enter temperature in Kelvin, molalities in mol/kg, and activity coefficients (typically between 0 and 1 for non-ideal solutions). All values must be positive.
Q1: What is an activity coefficient?
A: It's a correction factor that accounts for deviations from ideal solution behavior due to molecular interactions.
Q2: Why is temperature important in this calculation?
A: The EMF depends directly on temperature - higher temperatures generally increase the potential difference.
Q3: What does "without transference" mean?
A: It means the calculation assumes no ion migration between half-cells through a salt bridge or membrane.
Q4: How do I find activity coefficients?
A: They can be determined experimentally or estimated using Debye-Hückel theory for dilute solutions.
Q5: What if my EMF result is negative?
A: A negative EMF indicates the cell reaction is non-spontaneous in the direction written (the more concentrated solution is actually the anode).