Molarity and Normality Calculator
Standardizing a titrant or making a molar standard? Enter the mass weighed, the molecular weight, and the final volume to get molarity — plus normality using the equivalents per mole for your reaction.
Solution Strength
| Item | Value |
|---|
How the calculation works
Formulas
Moles = mass (g) / molecular weight (g/mol)
Molarity (M) = moles / volume (L)
Normality (N) = Molarity × equivalents per mole
Equivalent weight = molecular weight / equivalents per mole
Moles = mass (g) / molecular weight (g/mol)
Molarity (M) = moles / volume (L)
Normality (N) = Molarity × equivalents per mole
Equivalent weight = molecular weight / equivalents per mole
| Common titrant | Equivalents per mole |
|---|---|
| HCl, NaOH, HNO₃ | 1 |
| H₂SO₄ | 2 |
| Na₂S₂O₃ (iodometric) | 1 |
| K₂Cr₂O₇ (COD) | 6 |
| KMnO₄ (acidic) | 5 |
Notes & limitations
Molarity is moles of solute per liter of solution; normality is equivalents per liter, where equivalents depend on the reaction (Standard Methods, Section 1010; Harris, Quantitative Chemical Analysis). The table lists equivalents for titrants common in water labs — confirm against your method’s reaction.
- Equivalents per mole depend on the reaction, not just the formula — permanganate is 5 in acid but 3 in neutral solution. Use the value for your method.
- For primary standards (e.g. potassium hydrogen phthalate), dry per the method before weighing.
- Normality is being phased out of some methods in favor of molarity — check which unit your SOP requires before labeling.
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