# What mass of NaCl is needed to make 2.50 L of a 2.20 M of a NaCl Solution?

Mar 4, 2018

$\text{321 g}$

#### Explanation:

All you need to know here is that the molarity of a solution tells you the number of moles of solute present in exactly $\text{1 L}$ of the solution.

In your case, a $\text{2.20-M}$ sodium chloride solution will contain $2.20$ moles of sodium chloride, the solute, for every $\text{1 L}$ of the solution.

So if every $\text{1 L}$ of this solution must contain $2.20$ moles of sodium chloride in order for the solution to have a molarity of $\text{2.20 M}$, it means that $\text{2.50 L}$ of this solution must contain

2.50 color(red)(cancel(color(black)("L solution"))) * "2.20 moles NaCl"/(1color(red)(cancel(color(black)("L solution")))) = "5.50 moles NaCl"

To convert the number of moles of sodium chloride to grams, use the molar mass of the compound.

$5.50 \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{moles NaCl"))) * "58.4 g"/(1color(red)(cancel(color(black)("mole NaCl")))) = color(darkgreen)(ul(color(black)("321 g}}}}$

The answer is rounded to three sig figs.