pH ácido forte
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The strong acid pH calculator is used to determine the pH of solutions containing strong acids, which fully dissociate in water. The pH is calculated using the formula pH = -log[H⁺], where [H⁺] is the hydrogen ion concentration. For monoprotic acids (e.g., HCl), [H⁺] equals the acid concentration. For diprotic acids (e.g., H₂SO₄), multiply the concentration by the number of H⁺ ions released.
This tool is ideal for analytical chemistry, especially in school or industrial labs. Simply input the acid's molarity and confirm if it is monoprotic or diprotic. The calculator automatically computes the pH based on the acid's complete dissociation. Example: a 0.01 mol/L HCl solution has pH = -log(0.01) = 2.
Note that this calculator only works with strong acids (e.g., HCl, H₂SO₄, HNO₃). Weak acids (like CH₃COOH) follow a different logic due to incomplete dissociation. Concentration must be in mol/L, and temperature is assumed to be 25°C, as dissociation constants vary with heat.
Frequently asked questions
How does it work for diprotic acids?
For diprotic acids like H₂SO₄, the H⁺ concentration is double the acid concentration. Example: 0.1 mol/L H₂SO₄ releases 0.2 mol/L H⁺, resulting in pH = -log(0.2) ≈ 0.7.
Can I use this for weak acids?
No, because weak acids don't fully dissociate. Use a calculator that accounts for the dissociation constant (Ka) instead.
Do I need to convert concentration units?
Yes, concentration must be in mol/L. If in grams/L, convert using the acid's molar mass.
Why doesn't it consider temperature?
The standard formula (pH = -log[H⁺]) assumes 25°C. Other temperatures require recalculating the water dissociation constant (Kw).