# Question 12208

Apr 13, 2017

$\text{8.19% v/v}$

#### Explanation:

A solution's volume by volume percent concentration, $\text{v/v %}$, tells you the number of milliliters of solute present in $\text{100 mL}$ of solution.

You already know the number of milliliters present in $\text{359 mL}$ of solution, so all that you need to do here is to use the known composition of the solution as a conversion factor to figure out how many milliliters of ethanol would be present in $\text{100 mL}$ of solution.

Keep in mind that you can do this because solutions are homogeneous mixtures, i.e. they same the same composition throughout.

You will have

100 color(red)(cancel(color(black)("mL solution"))) * "29.4 mL ethanol"/(359color(red)(cancel(color(black)("mL solution")))) = "8.19 mL ethanol"#

This means that the solution's volume by volume percent concentration is equal to

$\textcolor{\mathrm{da} r k g r e e n}{\underline{\textcolor{b l a c k}{\text{% v/v = 8.19% ethanol}}}}$

The answer is rounded to three sig figs.