The molar mass of potassium permanganate (KMnO4) is 158.032 g/mol.
Case matters: CO is carbon monoxide, Co is
cobalt. Brackets and hydrates are fine — try
or
.
| Element | Atoms | Atomic mass | Mass contributed | Percent |
|---|---|---|---|---|
| Potassium (K) | 1 | 39.0983 | 39.098 | 24.74% |
| Manganese (Mn) | 1 | 54.938043 | 54.938 | 34.76% |
| Oxygen (O) | 4 | 15.999 | 63.996 | 40.50% |
| Total | 6 | 158.032 | 100.00% |
39.098 + 54.938 + 63.996 = 158.032 g/mol
Grams and moles
25 g of potassium permanganate is 0.1582 mol, because 25 ÷ 158.032 = 0.1582.
This element has no single atomic weight. Their isotopic mix varies slightly depending on where on Earth the sample came from, so the figure used here is the conventional value IUPAC publishes for when one number is needed: oxygen is 15.999, and really lies between 15.99903 and 15.99977.
Potassium permanganate is 158.032 g/mol: potassium 39.098, manganese 54.938 and four oxygens totalling 63.996. It is the deep purple solid in every stockroom, and a few crystals colour a litre of water visibly.
The formula is worth reading carefully. MnO4 with a single negative charge is permanganate, and manganese sits at oxidation state +7. MnO4 with a double negative charge is manganate, where manganese is +6. Same formula, same atoms, same molar mass for the ion itself, and the difference is charge alone rather than an extra oxygen. Explaining them as though one has more oxygen than the other teaches the single thing about the pair that is false.
Because permanganate is intensely coloured and turns almost colourless when reduced, it serves as its own indicator in titrations. The endpoint is the first faint pink that persists, and no separate indicator is added.