This normality calculator converts between molarity and normality (N = M × equivalents per mole) and weighs out a target solution: grams = N × equivalent weight × litres.
| Normality N | – |
| Equivalent weight (MW ÷ n) | – |
| Grams to weigh for the volume | – |
n-factor by reaction: acids → H⁺ donated (H₂SO₄ = 2, HCl = 1, H₃PO₄ = 1–3 by endpoint), bases → OH⁻ or H⁺ accepted, redox agents → electrons transferred, salts → total positive charge. The same bottle can carry different normalities for different reactions — normality is a property of the reaction, not just the solution.
The Old Concentration Unit That Refuses to Retire
Its modern partner units are our Molarity and Molality Calculators. Part of our Chemistry Calculators collection.
Worked Examples (Verified)
- 0.5 M H₂SO₄ (defaults): N = 0.5 × 2 = 1.0 N · equivalent weight 98.08/2 = 49.04 g/eq · weighing out 500 mL of it takes N × EW × V = 1.0 × 49.04 × 0.5 = 24.52 g (cross-check: 0.5 L × 0.5 mol/L × 98.08 g/mol = 24.52 g — the two ledgers agree)
- 500 mL of 0.1 N H₂SO₄ (a common bench prep): 0.1 × 49.04 × 0.5 = 2.452 g
- Why titrations loved normality: at the equivalence point, N₁V₁ = N₂V₂ works regardless of the reaction’s mole ratio — the equivalents were engineered to cancel stoichiometry
Normality Discipline
- Always declare the reaction: “1 N H₂SO₄” is unambiguous only because full neutralization (n = 2) is the default reading; H₃PO₄ can be 1, 2 or 3 N per mole depending on endpoint.
- Redox normality rides on electrons: KMnO₄ in acid takes 5 e⁻ (n = 5); in neutral/alkaline media it takes 3 — same bottle, different N.
- Modern IUPAC prefers molarity + explicit stoichiometry; normality survives in water treatment, clinical and pharmacopeia methods — legacy units persist where protocols do.
- meq/L (milliequivalents) is normality × 1000 — the clinical dialect of the same idea.
Related Tools
- Molarity Calculator — moles per litre
- Titration Calculator — equivalence points
- Chemistry Calculators — the full collection
Frequently Asked Questions
How do you calculate normality?
N = molarity × equivalents per mole (n-factor). 0.5 M H₂SO₄ with n = 2 is 1.0 N. Equivalently, N = grams ÷ (equivalent weight × litres), where equivalent weight = molar mass ÷ n. This calculator computes N, the equivalent weight, and the grams for a target volume.
What is the n-factor?
The number of reactive units each formula unit supplies in the reaction at hand: H⁺ ions for acids, OH⁻ (or H⁺ accepted) for bases, electrons for redox agents, total cation charge for salts. It depends on the reaction — H₃PO₄ neutralized to H₂PO₄⁻ has n = 1; fully to PO₄³⁻, n = 3.
How many grams make 500 mL of 0.1 N H₂SO₄?
Equivalent weight = 98.08/2 = 49.04 g/eq. Grams = 0.1 eq/L × 49.04 g/eq × 0.5 L = 2.452 g. At 1.0 N the same volume takes ten times more (24.52 g) — normality scales the scale directly.
Why does normality exist if molarity does?
History and convenience: equivalents were designed so equal volumes of equal-normal solutions neutralize exactly (N₁V₁ = N₂V₂), hiding stoichiometric ratios inside the unit. Molarity won the modern standard because normality’s reaction-dependence invites ambiguity — but legacy protocols still specify N.
What is a milliequivalent?
One-thousandth of an equivalent: concentration in meq/L = N × 1000. Clinical labs report electrolytes this way (Na⁺ ≈ 140 meq/L) because charge balance — equivalents’ home turf — is what physiology keeps books in.
Is this normality calculator free?
Yes — free, instant, no sign-up.