Isopropyl alcohol (rubbing alcohol) is prepared by mixing 72.0 mL of isopropyl alcohol in 28.0 mL of water. Compute the % by volume of isopropyl and the % by volume of the water in the alcohol.
Answers
Answer:
u
Explanation:
Explanation:
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.
Given info : Isopropyl alcohol (rubbing alcohol) is prepared by mixing 72.0 mL of isopropyl alcohol in 28.0 mL of water.
To find : Compute the % by volume of isopropyl and the % by volume of the water in the alcohol.
solution : percentage of isopropyl alcohol = volume of alcohol/volume of solution × 100
= 72ml/(72 ml + 28 ml) × 100
= 72 % (v/V)
therefore the percentage of isopropyl by volume is 72%.
percentage of water in the solution by volume = 100 % - percentage of isopropyl alcohol in the solution by volume
= 100 % - 72 % = 28 %
therefore the percentage of the water in the alcohol solution is 28% by volume.