How this calculator works
An equivalent counts the reaction capacity of a species, such as transferred protons or electrons in a specified balanced reaction. Equivalent weight is molar mass divided by equivalents per mole. Divide grams by g/eq to obtain equivalents, then divide by final litres of solution. Read the normality result in eq/L and supply equivalent weight in g/eq. Mass and solution volume can use any of their listed units.
Formula
Equivalent weight E = molar mass / reaction equivalents per mole. Normality N = mass (g) / [E (g/eq) x volume (L)].
Worked example
Dissolving 4.9 g with equivalent weight 49 g/eq to a final 0.5 L gives 0.1 eq and 0.2 eq/L. A 2 L solution at 0.1 eq/L with E = 40 g/eq needs 8 g.
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Frequently asked questions
Is normality fixed by the chemical name?
No. A species can participate with different reaction capacities, so the balanced reaction must be stated.
Can I enter solvent volume?
Use final solution volume after dissolution. The initial solvent amount need not equal that volume.
Is normality the same as molarity?
They are equal only when the specified reaction has one equivalent per mole; otherwise N equals molarity times the equivalents per mole.