# Question #3501f

Mar 7, 2017

${\text{20 moles BaCl}}_{2}$

#### Explanation:

Molarity is simply a measure of the number of moles of solute present in $\text{1 L}$ of solution.

In your case, a $\text{3 M}$ barium chloride solution will contain $3$ moles of barium chloride, $\text{BaCl} 2$, for every $\text{1 L}$ of solution.

As you know, solutions are homogeneous mixtures, which means that they have the same composition throughout. This implies that the molarity of the solution can be used as a conversion factor.

Since you know that $\text{1 L}$ of this solution contains $3$ moles of solute, you can scale up this known composition to determine the number of moles of solute present in $\text{6.5 L}$ of solution

$6.5 \textcolor{red}{\cancel{\textcolor{b l a c k}{{\text{L solution"))) * overbrace("3 moles BaCl"_2/(1color(red)(cancel(color(black)("L solution")))))^(color(blue)("= 3 M")) = color(darkgreen)(ul(color(black)("20 moles BaCl}}_{2}}}}$

The answer is rounded to one significant figure, the number of sig figs you have for the molarity of the solution.