Calculate the volume of a 26 % ($\rho_S=$ 1.1288 $\frac{g}{mL}$) solution $S$ of chlorhydric acid
that must be diluted in a volumetric flask $j$ of 1000 $mL$ in order to obtain a solution with $pH$ = 2.06
$HCl$: strong acid
Final solution:
$c$ $=$ $10^{-pH}$ =
$10^{-2.06}$ =
0.15 $\frac{mol}{L}$
$n_{HCl}$ =
$c_{HCl}\cdot V_{j}$ =
0.15$\cdot$1 =
0.15$\;mol$
The initial concentrated solution had the same number of moles:
Initial solution $S$:
$m_{HCl}$ =
$n_{HCl}\cdot M_{HCl}$ =
0.15$\cdot$36.47 =
5.471$\;g$
$m_S$ =
$\frac{m_{HCl}\cdot 100}{\%_S}$ =
$\frac{5.471\cdot 100}{26}$ =
21.042$\;g$
$V_S$ =
$\frac{m_S}{\rho_S}$ =
$\frac{5.471}{1.1288}$ =
4.847$\;mL$
