Question

A student wants to prepare a solution of acetic acid and water having 30% v/v. If 6 mL of acetic acid has been taken then how much water must be added to get the desired concentration?

• A. 20 mL
• B. 24 mL
• C. 14 mL
• D. 10 mL

Answer 1

The correct option is C 14 mL

Given:
Volume of solute (acetic acid) = 6 mL
Concentration (v/v) of solution = 30%

To find:
The amount of water (in mL) required to get the desired concentration of 30% v/v.

Solution:
Let the volume of water (solvent) required to be x.
So, the volume of solution $=6+x$

We know that,
Concentration of a solution (v/v%) $=\frac{\text{Volume of solute}}{\text{Volume of solution}}\times 100$

$\Rightarrow \frac{6}{6+x}\times 100=30$
$\Rightarrow 600=180+30x$
$\Rightarrow 30x=600-180$
$\Rightarrow x=\frac{420}{30}$
$\Rightarrow x=14\text{mL}$
Therefore, 14 mL of water will be required.