Question

How many millilieters of a 12% (v/v) propyl alcohol solution would you need to obtain 5.7 mL of propyl alcohol?

Answer 1

`"48 mL"`

Explanation:

A solution's volume by volume percent concentration, `"% v/v"`, is a measure of how many milliliters of solute it contains in `"100 mL"` of solution.

In your case, a `"12% v/v"` solution will contain `"12 mL"` of solute for every `"100 mL"` of solution.

This means that in order to have `"5.7 mL"` of solute, you need to have

`5.7 color(red)(cancel(color(black)("mL solute"))) * "100 mL solution"/(12color(red)(cancel(color(black)("mL solute")))) = color(darkgreen)(ul(color(black)("48 mL solution")))`

The answer is rounded to two sig figs.