Question

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

• A. $20mL$ of water
• B. $24mL$ of water
• C. $14mL$ of water
• D. $10mL$ of water

Answer 1

The correct option is C $14mL$ of water

Given: Volume of solute (acetic acid) $=6mL$
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%) $=\frac{Volumeofsolute}{Volumeofsolution}\times 100$
$\Rightarrow \frac{6}{6+x}\times 100=30$
$\Rightarrow 600=180+30x$
$\Rightarrow 30x=600-180$
$\Rightarrow x=\frac{420}{30}$
$x=14mL$