Activity of Cathodic Electrolyte of Concentration Cell with Transference given Valencies Calculator

Cathodic Ionic Activity Formula:

\[ a_2 = \exp\left(\frac{E_{cell} \cdot \nu_{\pm} \cdot Z_{\pm} \cdot F}{t_- \cdot \nu \cdot R \cdot T}\right) \cdot a_1 \]

EMF of Cell:

Number of Positive/Negative Ions:

Valencies of Ions:

Transport Number of Anion:

Total Number of Ions:

Temperature:

Anodic Ionic Activity:

mol/kg

Cathodic Ionic Activity (mol/kg):

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1. What is Cathodic Ionic Activity?

Definition: Cathodic Ionic Activity is the measure of the effective concentration of a molecule or ionic species in a cathodic half-cell.

Purpose: This calculator determines the activity of ions in the cathodic electrolyte of a concentration cell with transference, accounting for valencies of ions.

2. How Does the Calculator Work?

The calculator uses the Nernst equation modified for transference:

\[ a_2 = \exp\left(\frac{E_{cell} \cdot \nu_{\pm} \cdot Z_{\pm} \cdot F}{t_- \cdot \nu \cdot R \cdot T}\right) \cdot a_1 \]

Where:

\( a_2 \) — Cathodic ionic activity (mol/kg)
\( E_{cell} \) — EMF of the cell (V)
\( \nu_{\pm} \) — Number of positive/negative ions
\( Z_{\pm} \) — Valencies of ions
\( F \) — Faraday constant (96485.33212 C/mol)
\( t_- \) — Transport number of anion
\( \nu \) — Total number of ions
\( R \) — Gas constant (8.314 J/mol·K)
\( T \) — Temperature (K)
\( a_1 \) — Anodic ionic activity (mol/kg)

3. Importance of Ionic Activity Calculation

Details: Accurate ionic activity calculations are essential for understanding electrochemical cell behavior, predicting reaction rates, and designing batteries and corrosion protection systems.

4. Using the Calculator

Tips: Enter all required parameters including EMF, ion counts, valencies, transport number, temperature, and anodic activity. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the transport number of an anion?
A: It's the fraction of total current carried by the anion in the electrolyte (typically between 0 and 1).

Q2: Why does temperature affect ionic activity?
A: Temperature influences ion mobility and the equilibrium between ion pairs and free ions in solution.

Q3: What are typical values for ionic activity?
A: For dilute solutions, activity approaches concentration (mol/kg). For concentrated solutions, activity coefficients typically range from 0.1 to 1.5.

Q4: How do I determine the number of positive/negative ions?
A: This depends on your electrolyte's dissociation. For NaCl, it would be 1 (Na+) and 1 (Cl-), so enter 1.

Q5: What if my transport number is unknown?
A: Typical values are 0.4-0.6 for many salts. Consult literature for your specific electrolyte.