Chemistry
Molar mass from mass and moles
The definition. Divide the mass of a sample in grams by the amount of substance in moles to get grams per mole.
The Formula
M = m / n
The definition. Divide the mass of a sample in grams by the amount of substance in moles to get grams per mole.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| m | Mass of the sample | grams | Measured on a balance, in grams. |
| n | Amount of substance | moles | The number of moles in that sample. |
| M | Molar mass | grams per mole | A constant for the substance, in grams per mole. |
What Each Symbol Means
mgrams
Mass of the sample
Measured on a balance, in grams.
nmoles
Amount of substance
The number of moles in that sample.
Mgrams per mole
Molar mass
A constant for the substance, in grams per mole.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate molar mass page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Molar Mass, filed under Science. Every number the guide produces comes from substituting into this one line.