Is molecular mass different than the molar mass?

Question

I thought that molar mass is the mass of one mole of a substance whereas molecular mass is the mass of one molecule of a substance.

But the molecular mass of water is 18.2 u, which is similar to its molar mass i.e. 18.02 g/mol.

Are these two different and how?

33 kilograms of something and 33 grams of it look pretty similar in writing. They feel different, though. — Ivan Neretin, Jun 11 '19 at 11:11
The molecular mass is the mass of one molecule in amu (atomic mass units). — Michael Lautman, Jun 11 '19 at 13:28
Related: Quick and simple explanation of molar mass, molecular mass and atomic mass and How are the molar mass and molecular mass of any compound numerically the same?. — , Jun 11 '19 at 14:24
That is like saying my car can go 92 mph, and the distance from home to the big city is 92 miles, so those two are similar. However, one is a speed and the other a distance. (And the reason they are similar is because in my world, an hour is defined as the time it takes my car to go to the big city at maximal speed). — Karsten, Jun 11 '19 at 15:11

score 0 · Answer 1 · edited Jun 11 '19 at 16:29

Molecular mass is the mass of a single molecule

Molar mass refers to the mass of 1 mole of molecules, ie $ 6.023 × 10^{23}$ of them.

Eg: Molecular mass of $\ce{H2}$ is about $3.32 \times 10 ^{-24}\ \mathrm g$ or about $2\ \mathrm u$.

Here "$\mathrm u$" is just a unit,

$1\ \mathrm u = 1.66 \times 10^{-24}\ \mathrm g$

Whereas molar mass is about $2\ \mathrm{g/mol}$.

1 Answers1