Equivalent Weight

Definition

The amount of a substance needed to do a fixed amount of chemistry, in alkalinity terms the amount needed to neutralize one mole of hydrogen ion.

Molecular weight tells you how much a mole weighs, while equivalent weight tells you how much is needed to neutralize one H+. Hydroxide and bicarbonate each neutralize one H+, while carbonate neutralizes two, so their equivalent weights differ from a simple mass comparison. Calcium carbonate weighs 100 g per mole and neutralizes 2 H+, giving an equivalent weight of 100 divided by 2 equals 50 g/eq.

Related concepts

mg or L as Calcium Carbonate · Milliequivalents per Liter · Alkalinity

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Part of The Blueprint of Water · 📏 measurement