Answer to Question #269492 in General Chemistry for john

Question

calculate the percent by volume of the disinfectant aki made. Units in mL

Answer 1

We express a solution's volume by volume percent concentration, % v/v

, by calculating how many milliliters of solute are present in 100 mL

 of solution.

In essence, all you have to do to determine a solution's volume by volume percent concentration is figure out how many milliliters of solute you get in 100 mL

 of solution, then tag along a %

 sign to that value.

In your case, you know that you get 18.9 mL

 of isopropyl alcohol, your solute, in a total volume of

V

total

=

V

solute

+

V

solvent

V

total

=

18.9 mL

+

412 mL

=

430.9 mL

of solution. In order to find the solution's % v/v

 concentration, you must pick pick a 100 mL

 of this solution and use its known composition to calculate how many milliliters of isopropyl alcohol it contains

100

mL solution

⋅

the solution's composition

18.9 mL isopropyl alcohol

430.9

mL solution

=

4.39 mL isopropyl alcohol

Now all you have to do is replace the mL

 symbol with a %

 sign

% v/v

=

4.39 mL isopropyl alcohol

100 mL solution

=

∣

∣

∣

∣

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

4.39

%

a

a

∣

∣

−−−−−−−−−−−

The answer is rounded to three sig figs.