Molar MassMolar mass of salts
A salt is the ionic compound left when an acid is neutralised by a base. Salts have no separate molecules, so chemists speak of the mass of one formula unit.
Read the formula of a salt carefully before counting. Brackets with a number, as in aluminium sulphate or calcium phosphate, multiply everything inside. Many salts in the laboratory are sold as hydrates, so check the label of the bottle: the anhydrous salt on this page and its hydrate have different molar masses.
This page lists 46 salts with their formulas and molar masses, lightest first. The lightest here is sodium fluoride at 41.99 g/mol and the heaviest is lead(II) iodide at 461.00 g/mol. Tap a name for the full working, the percentage of each element and worked examples.
| Compound | Formula | Molar mass, g/mol |
|---|---|---|
| Sodium fluoride | NaF | 41.99 |
| Ammonium chloride sal ammoniac | NH4Cl | 53.49 |
| Sodium chloride common salt | NaCl | 58.44 |
| Calcium carbide | CaC2 | 64.10 |
| Sodium nitrite | NaNO2 | 69.00 |
| Sodium hypochlorite the active part of liquid bleach | NaClO | 74.44 |
| Potassium chloride muriate of potash | KCl | 74.55 |
| Calcium fluoride fluorite | CaF2 | 78.07 |
| Ammonium nitrate | NH4NO3 | 80.04 |
| Sodium hydrogencarbonate sodium bicarbonate | NaHCO3 | 84.01 |
| Sodium nitrate Chile saltpetre | NaNO3 | 84.99 |
| Magnesium chloride | MgCl2 | 95.21 |
| Calcium carbonate limestone | CaCO3 | 100.09 |
| Potassium nitrate saltpetre | KNO3 | 101.10 |
| Sodium carbonate soda ash; washing soda when hydrated | Na2CO3 | 105.99 |
| Calcium chloride | CaCl2 | 110.98 |
| Potassium bromide | KBr | 119.00 |
| Magnesium sulphate anhydrous magnesium sulfate | MgSO4 | 120.36 |
| Potassium chlorate | KClO3 | 122.55 |
| Ammonium sulphate ammonium sulfate | (NH4)2SO4 | 132.13 |
| Aluminium chloride | AlCl3 | 133.33 |
| Copper(II) chloride cupric chloride | CuCl2 | 134.45 |
| Calcium sulphate anhydrite | CaSO4 | 136.13 |
| Zinc chloride | ZnCl2 | 136.28 |
| Potassium carbonate potash | K2CO3 | 138.20 |
| Sodium sulphate sodium sulfate | Na2SO4 | 142.04 |
| Silver chloride | AgCl | 143.32 |
| Iron(II) sulphate ferrous sulfate | FeSO4 | 151.90 |
| Potassium permanganate potassium manganate(VII) | KMnO4 | 158.03 |
| Sodium thiosulphate sodium thiosulfate | Na2S2O3 | 158.10 |
| Copper(II) sulphate anhydrous copper sulfate | CuSO4 | 159.60 |
| Zinc sulphate zinc sulfate | ZnSO4 | 161.44 |
| Iron(III) chloride ferric chloride | FeCl3 | 162.19 |
| Sodium phosphate trisodium phosphate | Na3PO4 | 163.94 |
| Potassium iodide | KI | 166.00 |
| Silver nitrate lunar caustic | AgNO3 | 169.87 |
| Potassium sulphate sulphate of potash | K2SO4 | 174.25 |
| Barium sulphate barium sulfate | BaSO4 | 233.39 |
| Mercury(II) chloride corrosive sublimate | HgCl2 | 271.49 |
| Potassium dichromate potassium dichromate(VI) | K2Cr2O7 | 294.18 |
| Lead(II) sulphate lead sulfate | PbSO4 | 303.26 |
| Calcium phosphate tricalcium phosphate | Ca3(PO4)2 | 310.17 |
| Lead(II) nitrate lead nitrate | Pb(NO3)2 | 331.21 |
| Aluminium sulphate aluminum sulfate | Al2(SO4)3 | 342.13 |
| Iron(III) sulphate ferric sulfate | Fe2(SO4)3 | 399.86 |
| Lead(II) iodide | PbI2 | 461.00 |
Which values? This site uses the abridged standard atomic weights published by IUPAC (CIAAW), read on 12 November 2026. Your textbook or question paper may round them differently, for example H = 1 and O = 16, so its answer can differ slightly. In an exam, use the values the paper gives.
Not in the list?
Type any formula into the calculator. It handles brackets and water of crystallisation and shows the same working as these pages. The method by hand is on the step by step page.
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