How to Calculate Hydrogen Ion Concentration [H⁺]
Calculate acidity and basicity parameters step-by-step:
Choose Metric
Select [H⁺], [OH⁻], pH, or pOH input option.
Enter Value
Input concentration in Molar (mol/L) or pH unit.
Apply Kw Constant
Uses Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ M² self-ionization equilibrium.
Classify Solution
Get instant acidic (pH < 7), neutral (pH = 7), or basic (pH > 7) rating.
Key Features & Logarithmic Scales
4-Way Instant Conversion
Computes [H⁺], [OH⁻], pH, and pOH simultaneously in real-time.
Scientific Exponent Support
Parses scientific notation like 2.5e-4 M or 1e-12 M cleanly.
Acidity & Basicity Scale
Evaluates solution state across standard 0 to 14 pH scale.
Aqueous Chemistry Guide: [H⁺] & pH Scale
In aqueous solutions, hydrogen ions (protons, H⁺ or hydronium H₃O⁺) determine solution acidity. The pH scale is defined as the negative logarithm of hydrogen ion concentration:pH = -log₁₀[H⁺] ⇒ [H⁺] = 10^(-pH)
Because water self-ionizes (2H₂O ⇌ H₃O⁺ + OH⁻) with ion product Kw = 1.0 × 10⁻¹⁴ M² at 25°C, pH + pOH = 14.00 holds true for all aqueous solutions.
Frequently Asked Questions
?Can pH be negative or greater than 14?
Yes. Extremely concentrated strong acids (e.g. 12M HCl) can have a negative pH (~ -1.08), while concentrated bases (e.g. 10M NaOH) can have pH > 14.