Equivalent Weight of Sodium Bisulfate
| Value | 0.120054 kg/mol |
| Status | Measured: ± 0.00002 kg/mol (0.00017 relative) |
| Source | IUPAC |
| Categories | Chemistryequivalent-weightwater-treatment |
| gram per mole | 120.054 g/mol |
| kilogram per kilomole | 120.054 kg/kmol |
| milligram per millimole | 120.054 mg/mmol |
| pound per pound-mole | 120.054 lb/lb-mol |
| dalton (as molar mass) | 120.054 Da |
| kilogram per mole | 0.120054 kg/mol |
| kilodalton (as molar mass) | 0.120054 kDa |
Learning zone
Sodium bisulfate is what remains after sulfuric acid has spent one of its two protons on caustic soda, and the proton it keeps is still a strong one — HSO₄⁻ has a pKa of about 1.99, so it titrates completely against alkalinity. One proton per formula unit makes the equivalent weight the whole formula mass: 22.990 + 1.008 + 32.06 + 4 × 15.999 = 120.054 g/eq. That is 2.4 times sulfuric acid's 49.036, which is the price of the convenience — you haul, store and dissolve two and a half times the product mass for the same alkalinity knocked out.
The convenience is real, though: a dry granular solid with no fume, no drum of concentrated acid, and a spill you sweep up rather than neutralise. It is sold as "dry acid" for pools and spas and as pH-down granules for a dozen small-system uses, and it is often the only acid a site without proper chemical containment should be handling. The anion story matches its parent acid — every equivalent adds sulfate — and supplier sheets that print 120.06 g/mol are carrying a rounding from the older sulfur atomic weight; the IUPAC 2021 arithmetic gives 120.05.