# How do we determine molar concentrations from concentrations that are reported in "ppm"?

$\text{1 ppm}$ $=$ $1 \cdot m g \cdot {L}^{-} 1$
When we deal in $\text{ppm}$ concentrations, typically the solute is so dilute, that the density of the solution does not change very much from that of water, i.e. $1 \cdot g \cdot m {L}^{-} 1$.