E

Equivalent Weight

Eq. wt = M/n (g/equiv)
Quick Reference
Formula / NotationEq. wt = M/n (g/equiv)
Also Known AsGram equivalent weight; equivalent mass; Eq. wt; n-factor weight; normality basis

What is Equivalent Weight?

Equivalent weight is the mass of a substance (in grams) that reacts with or is equivalent to one mole of hydrogen ions (for acids/bases) or one mole of electrons (for redox reactions). It equals the molar mass divided by the number of reactive units (n): Eq. wt = M/n. Equivalents and normality (equivalents/litre) are based on this concept.

Formula & Notation

Eq. wt = M/n (g/equiv)

Other Names / Synonyms: Gram equivalent weight; equivalent mass; Eq. wt; n-factor weight; normality basis

Properties & Characteristics

Eq. wt = M/n; n = number of H⁺ or OH⁻ supplied per formula unit (acids/bases) or electrons transferred per formula unit (redox); unit: g/equivalent; for H₂SO₄: n = 2, Eq. wt = 98/2 = 49 g/equiv; for KMnO₄ in acid: n = 5, Eq. wt = 31.6 g/equiv

Uses & Applications

Older analytical chemistry and titration calculations; normality-based calculations; standardisation of acid/base solutions; redox titrations; pharmaceutical dosing calculations (historical); still used in some water chemistry and clinical applications

Safety Information

No hazard — a calculation concept. The chemicals whose equivalent weights are calculated may be hazardous.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Equivalent Weight
Formula Eq. wt = M/n (g/equiv)
Synonyms Gram equivalent weight; equivalent mass; Eq. wt; n-factor weight; normality basis

Frequently Asked Questions

Equivalent weight is the mass of a substance (in grams) that reacts with or is equivalent to one mole of hydrogen ions (for acids/bases) or one mole of electrons (for redox reactions). It equals the molar mass divided by the number of reactive units (n): Eq. wt = M/n. Equivalents and normality (equivalents/litre) are based on this concept.

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