Question

$29.2$% (W.W) $HCl$ stock solution has a density of $1.25g/mL$. The volume of stock solution required to prepare a $200mL$ solution of $0.4M$ $HCl$ is:

• A. $2$
• B. $4$
• C. $6$
• D. $8$

Answer 1

The correct option is D $8$

Given

Density of solution is 1.25 g/ml

29.2% (W/W) is HCl in it

To prepare

Molarity of HCl =0.4 M

Volume Of HCl = 200ml

Solution

We know that 29.2 g of HCl is present in 100 g of solution

Volume of solution = $\frac{massofsolution}{Densityofsolution}$

=100/1.25

=80ml

Moles of HCl= $\frac{29.2}{36.5}=0.8$

Where 36.5 g is molar mass of HCl

Molalrity of solution

$=\frac{0.8\ast 1000}{80}=10M$

To prepare 200ml of 0.4 M HCl

$M_1\ast V_1=M_2\ast V_2$

$M_1=10M$

$M_2=0.4M$

$V_2=200ml$

Putting the values

$V_1=8ml$

The correct option is D