Ionic Strength Calculator
Calculate ionic strength of solutions using ion concentrations and charges
Calculate Ionic Strength
Ion Concentrations and Charges
Ionic Strength Results
Formula: I = ½ × Σ(ci × zi²)
Calculation: I = ½ × () = 0.0000 mol/L
Description: Ideal solution behavior, activity coefficients ≈ 1
Theory: Extended Debye-Hückel applicable
Example Solutions
Physiological Saline (0.9% NaCl)
Isotonic saline solution
Medical applications, cell culture
Seawater (simplified)
Simplified seawater composition
Environmental chemistry, marine biology
Buffer Solution (PBS)
Phosphate buffered saline
Biochemical research, protein studies
High Ionic Strength (1M CaCl₂)
High ionic strength solution
Protein precipitation, DNA extraction
Ionic Strength Guide
I < 0.01 mol/L
Very Dilute
Ideal solution behavior
0.01 - 0.1 mol/L
Dilute
Debye-Hückel applicable
0.1 - 1.0 mol/L
Moderate
Significant ion interactions
I > 1.0 mol/L
High Ionic Strength
Complex behavior
Common Compounds
Applications
Understanding Ionic Strength
What is Ionic Strength?
Ionic strength is a measure of the total concentration of ions in a solution. It quantifies the electrical environment in the solution and is crucial for understanding the behavior of electrolytes, activity coefficients, and various chemical and biological processes.
Key Concepts
- •Ion Concentration: Molarity or molality of individual ions
- •Charge Number: The charge on each ion (zi)
- •Activity Coefficients: Deviation from ideal behavior
Ionic Strength Formula
General Formula
I = ½ × Σ(ci × zi²)
I = Ionic strength (mol/L or mol/kg)
ci = Concentration of ion i
zi = Charge of ion i
Σ = Sum over all ions
From Molarity
ci = M × ni
M = Molarity of compound
ni = Number of ions of type i
Applications and Importance
Debye-Hückel Theory
Predicts activity coefficients in electrolyte solutions based on ionic strength.
Biochemical Systems
Controls protein folding, enzyme activity, and membrane potential in biological systems.
Environmental Chemistry
Water quality assessment, soil chemistry, and environmental modeling.
Example: NaCl Solution
Problem Setup
Compound: 0.1 M NaCl
Dissociation: NaCl → Na⁺ + Cl⁻
Ion concentrations: [Na⁺] = [Cl⁻] = 0.1 M
Calculation
I = ½ × (cNa⁺ × zNa⁺² + cCl⁻ × zCl⁻²)
I = ½ × (0.1 × 1² + 0.1 × 1²)
I = 0.1 mol/L