The molar mass of methanol (CH4O) is 32.042 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 |
|---|---|---|---|---|
| Carbon (C) | 1 | 12.011 | 12.011 | 37.49% |
| Hydrogen (H) | 4 | 1.0080 | 4.032 | 12.58% |
| Oxygen (O) | 1 | 15.999 | 15.999 | 49.93% |
| Total | 6 | 32.042 | 100.00% |
12.011 + 4.032 + 15.999 = 32.042 g/mol
Grams and moles
25 g of methanol is 0.7802 mol, because 25 ÷ 32.042 = 0.7802.
These elements have 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: carbon is 12.011, and really lies between 12.0096 and 12.0116; hydrogen is 1.0080, and really lies between 1.00784 and 1.00811; oxygen is 15.999, and really lies between 15.99903 and 15.99977.
Methanol is 32.042 g/mol, the smallest alcohol there is. Oxygen accounts for 49.93% of the mass, carbon 37.49% and hydrogen 12.58%.
It differs from ethanol by one carbon and two hydrogens, which is 14.027 g/mol, and that difference is the whole distance between a solvent and a drink. Methanol is metabolised to formaldehyde and then formic acid, and formic acid attacks the optic nerve. Ten millilitres can cause permanent blindness and around 100 millilitres is often fatal.
The two liquids look identical, smell similar and boil only eleven degrees apart, which is why industrial methanol is dyed and why improperly distilled spirits remain dangerous. No property you can check by eye distinguishes them.
The old name wood alcohol is literal: it was originally obtained by heating wood without air. Modern production runs from synthesis gas, and methanol is now a major feedstock for formaldehyde and acetic acid as well as a fuel in its own right.