Density of a solution ($\rho_S$)

The density of the solution is the ratio of the mass of solution to its volume:

$\rho_S$=$\frac{m_S}{V_S}$

Relative density of a solution ($d_S$)

The relative density of a solution is the ratio (without unit!) of the density of the solution by the density of the water at the same temperature:

$d_S$=$\frac{\rho_S}{\rho_{H_2O}}$
if the densities are given in the same unit

(Under the usual experimental conditions, the density of the water is approximately $1\frac{g}{mL}$)

Number of moles of solute ($n_{so}$)

The number of moles of the solute is the ratio of the mass of the solute to its molar mass.

$n_{so}$ $=$ $\frac{m_{so}}{M_{so}}$
if $m_{so}$ is given in g

Percentage of a solute ($ \%_{so}$)

The percentage of the solute is the ratio of the mass of the solute to the mass of the solution, multiplied by $100$ .

$\%_{so}$ $=$ $\frac{m_{so}\cdot 100}{m_S}$
if the masses are given in the same unit

Molar concentration (Molarity) of the solute ($ [so]$)

The molarity of the solute is the ratio of the number of moles of the solute to the volume of the solution.

$[so]$ $=$ $\frac{n_{so}}{V_S}$
if $V_S$ is expressed in L

Mass concentration (concentration expressed in $\frac{g}{L}$) of a solute ($ c_{so} $)

The mass concentration of the solute is the ratio of the mass of the solute to the volume of the solution.

$ c_{so}$ $=$ $\frac{m_{so}}{V_S}$
if $V_S$ is expressed in L and $m_{so}$ in g

The lattice

The following "lattice" summarizes the relationships between the previous quantities.

Each triangle symbolizes one of the previous definitions. For example, if we know $c_{so} $, $n_{so} $ and $[so]$, we compute $V_S $ by the green triangle, then $m_{so} $ by the purple triangle $ M_{so} $ by the red triangle!