pH of acids, bases and salts
Exercise 17

Calculate the mass of sodium hydroxide that must be dissolved in a volumetric flask $J$ of 1000 $mL$ in order to obtain a solution with $pH$ = 13.11.
$NaOH$: strong base
Final solution:
$pH$ $=$ $14$ $+$ $log\;[OH^-]$
$[OH^-]$ $=$ $10^{pH-14}$ =
0.13 $\frac{mol}{L}$
$c_{NaOH}$ $=$ $\frac{0.13}{1}$
$n_{NaOH}$ =
$c_{NaOH}\cdot V_{J}$ =
0.13$\cdot$1 =
0.13 $\;mol$
$m_{NaOH}$ =
$n_{NaOH}\cdot M_{NaOH}$ =
0.13$\cdot$40.01 =
5.201$\; g$