Equivalent Weight of Sodium Bicarbonate

Bicarbonate accepts a single proton, so sodium bicarbonate's equivalent weight is its whole formula mass: 22.990 + 1.008 + 12.011 + 3 × 15.999 = 84.006 g/eq. That is the heaviest equivalent among the common alkalis — each mg/L adds only 50.04/84.01 = 0.60 mg/L of alkalinity as CaCO₃ — and the inefficiency is precisely what it is chosen for. Bicarbonate cannot push pH past its own chemistry: dose as much as you like and the water settles toward the pH 8.3 boundary where bicarbonate dominates, which makes overdose essentially impossible.

That self-limiting character makes it the alkalinity source for sensitive applications — re-mineralising RO permeate, buffering a fish-bearing receiving stream, steadying a swimming pool — anywhere the goal is alkalinity without a pH excursion. The same substance under its bakery name, and as the "total alkalinity increaser" in every pool store, is dosed by exactly this arithmetic. Its limits are solubility, about 96 g/L at 20 °C, the lowest on the alkali shelf, and heat: above roughly 50 °C it sheds CO₂ and converts toward soda ash, quietly changing the equivalent weight of a hot day tank.