# How is molarity related to concentration?

Jan 14, 2017

In a one-sided way.

Molarity (units of $\text{M}$) is a type of concentration, and concentration isn't necessarily molarity.

$\text{M" = "mol solute"/"L solution}$,

whereas concentration is in general in units of any of the following:

• $\text{things"/"volume}$
(number concentration, such as number of particles in a certain volume)

• $\text{mass"/"volume}$
(density, or mass concentration)

• $\text{mol solute"/"L solution}$
(molality, or molar density)

• $\text{L of i"/"total L}$
(volume concentration, which I've never heard of, but it exists...)

• $\text{mass of i"/"total mass}$
(mass fraction, or parts per...; i.e. $\text{xg"/"yg}$, where $x$ and $y$ are prefixes such that the concentration is not numerically gigantic)

• $\text{mol solute"/"kg solvent}$
(molality)

• $\text{mols of i"/"total mols}$
(mol fraction)

• $\text{mols of i"/"mols of j}$
(mol ratio)

So clearly, there is more than just molarity when it comes to concentrations.