# Question 1a1fa

The formula for the percentage by volume of a substance $x$ is given by
$\underline{\overline{| \stackrel{\text{ ")(" "%"v/v"color(white)(l)x = ("volume of"color(white)(l)x)/("total volume") xx 100%" }}{|}}}$
For example, if we have $20$ $\text{mL}$ of ethanol ($\text{C"_2"H"_5"OH}$) mixed with $150$ $\text{mL}$ water, then the volume percentage of ethanol is
%"v/v C"_2"H"_5"OH" = (20color(white)(l)"mL C"_2"H"_5"OH")/(20color(white)(l)"mL C"_2"H"_5"OH" + 150color(white)(l)"H"_2"O") xx 100% = color(red)(11.8%#