# Question #5f7d6

Apr 11, 2017

$\text{189 mL}$

#### Explanation:

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

Your target solution must be $\text{25% v/v}$ formic acid, which means that it must contain $\text{25.0 mL}$ of formic acid, the solute, for every $\text{100 mL}$ of solution.

You can use the solution's percent concentration as a conversion factor to calculate the volume of formic acid that must be present in $\text{755 mL}$ of solution in order to have a $\text{25% v/v}$ solution.

$755 \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{mL solution"))) * overbrace("25.0 mL formic acid"/(100color(red)(cancel(color(black)("mL solution")))))^(color(blue)("= 25.0% v/v")) = color(darkgreen)(ul(color(black)("189 mL formic acid}}}}$

The answer is rounded to three sig figs.

You can thus say that adding $\text{189 mL}$ of formic acid to enough water to make the final volume of the solution equal to $\text{755 mL}$ will give you a $\text{25.0% v/v}$ formic acid solution.