Acid-Base Neutralization Calculator
Calculate the volume or concentration needed to neutralize an acid or base.
Supports HCl, H₂SO₄, H₃PO₄, NaOH, Ca(OH)₂, and custom compounds.
Acid-base neutralization occurs when the equivalents of acid exactly equal the equivalents of base.
The fundamental equation:
M_acid × V_acid × n_acid = M_base × V_base × n_base
Where:
- M = molarity (mol/L)
- V = volume (L or mL — must be consistent)
- n = number of H⁺ (for acids) or OH⁻ (for bases) per formula unit
n-factor values:
| Compound | Formula | n |
|---|---|---|
| Hydrochloric acid | HCl | 1 |
| Nitric acid | HNO₃ | 1 |
| Acetic acid | CH₃COOH | 1 |
| Sulfuric acid | H₂SO₄ | 2 |
| Phosphoric acid | H₃PO₄ | 3 |
| Sodium hydroxide | NaOH | 1 |
| Potassium hydroxide | KOH | 1 |
| Calcium hydroxide | Ca(OH)₂ | 2 |
| Aluminum hydroxide | Al(OH)₃ | 3 |
Why n matters: 1 mole of H₂SO₄ neutralizes 2 moles of NaOH (because H₂SO₄ donates 2 H⁺). 1 mole of Ca(OH)₂ neutralizes 2 moles of HCl (because Ca(OH)₂ provides 2 OH⁻).
Titration endpoint: At the equivalence point, the solution contains only salt and water (for strong acid/base). For example: HCl + NaOH → NaCl + H₂O (neutral solution). H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O
Indicators: Phenolphthalein: colorless below pH 8.2, pink above. Good for strong acid/strong base. Methyl orange: red below pH 3.1, yellow above 4.4. Good for strong acid/weak base.