# How do you calculate the grams solute required to make the following solution: 2.5 L of 0.90% of NaCl (m/v)?

May 13, 2017

Here's how you can do that.

#### Explanation:

You know that a solution's mass by volume percent concentration, $\text{% m/v}$, tells you the number of grams of solute present for every $\text{100 mL}$ of solution.

This implies that a $\text{0.90% m/v}$ solution will contain $\text{0.90 g}$ of sodium chloride, the solute, for every $\text{100 mL}$ of solution.

You can thus say that

2.5 color(red)(cancel(color(black)("L"))) * (10^3color(white)(.)"mL")/(1color(red)(cancel(color(black)("L")))) = 2.5 * 10^3 $\text{mL}$

of $\text{0.90% m/v}$ sodium chloride solution must contain

$2.5 \cdot {10}^{3} \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{mL solution"))) * "0.90 g NaCl"/(100color(red)(cancel(color(black)("mL solution"))))= color(darkgreen)(ul(color(black)("23 g NaCl}}}}$

The answer is rounded to two sig figs.