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.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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