Ionic Strength Calculator
Calculate the ionic strength of a solution from the concentrations and charges of dissolved ions.
Formula
I = ½ × Σ(cᵢ × zᵢ²)
- I = ionic strength (mol/L); cᵢ = concentration of ion i; zᵢ = charge number of ion i.
- For NaCl: Na⁺ and Cl⁻ both have z=1; I = 0.5 × (c×1 + c×1) = c.
- For MgSO₄: Mg²⁺ z=2, SO₄²⁻ z=2; I = 0.5 × (c×4 + c×4) = 4c.
- Used in Debye-Hückel theory for activity coefficients.
0.1 M NaCl solution
Inputs
- Ion 1 Concentration: 0.1 M
- Ion 1 Charge (|z|): 1
- Ion 2 Concentration: 0.1 M
- Ion 2 Charge (|z|): 1
- Ion 3 Concentration (optional): 0 M
- Ion 3 Charge (|z|): 1
I = 0.5 × (0.1×1 + 0.1×1) = 0.5 × 0.2 = 0.1 M.
Frequently asked questions
What is ionic strength used for?
Calculating activity coefficients, pH measurements, and protein stability in solutions.
How does ionic strength affect reactions?
Higher ionic strength can stabilize ions, affect solubility, and influence enzyme activity.