Question

Question #5f7d6

Answer 1

`"189 mL"`

Explanation:

The solution's volume by volume percent concentration, `"v/v %"`, tells you the number of milliliters of solute present for very `"100 mL"` of solution.

Your target solution must be `"25% v/v"` formic acid, which means that it must contain `"25.0 mL"` of formic acid, the solute, for every `"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 `"755 mL"` of solution in order to have a `"25% v/v"` solution.

`755 color(red)(cancel(color(black)("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 `"189 mL"` of formic acid to enough water to make the final volume of the solution equal to `"755 mL"` will give you a `"25.0% v/v"` formic acid solution.