# Question #73d8e

Nov 23, 2017

$\text{185 g H"_2"O}$

#### Explanation:

The solubility of sodium chloride in water tells you how many grams of sodium chloride can be added per $\text{100 g}$ of water in order to get a saturated solution of sodium chloride at a given temperature.

You know that at ${20}^{\circ} \text{C}$, a saturated solution of sodium chloride will contain $\text{36.0 g}$ of salt per $\text{100. g}$ of water.

Since a solution is a homogenous mixture, i.e. it has the same composition throughout, you can use the solubility of the salt at this temperature as a conversion factor to determine how many grams of water would be needed to make a saturated solution of sodium chloride that contains $\text{66.5 g}$ of solute.

$66.5 \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{g NaCl"))) * overbrace(("100. g H"_2"O")/(36.0color(red)(cancel(color(black)("g NaCl")))))^(color(blue)("the solubility of the salt at 20"^@"C")) = color(darkgreen)(ul(color(black)("185 g H"_2"O}}}}$

The answer is rounded to three sig figs, the number of sig figs you have for your values.

You can thus say that at ${20}^{\circ} \text{C}$, a saturated solution of sodium chloride, which is a solution in which the undissolved solid is in equilibrium with the solvated ions, contains $\text{66.5 g}$ of sodium chloride per $\text{185 g}$ of water.