Đáp án:
\(\begin{array}{l}
b)\\
{m_{{\rm{dd}}HCl}} = 125g\\
c)\\
{C_\% }NaCl = 8,36\%
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\\
NaOH + HCl \to NaCl + {H_2}O\\
b)\\
{m_{NaOH}} = 50 \times 20\% = 10g\\
{n_{NaOH}} = \dfrac{{10}}{{40}} = 0,25\,mol\\
{n_{HCl}} = {n_{NaOH}} = 0,25\,mol\\
{m_{HCl}} = 0,25 \times 36,5 = 9,125g\\
{m_{{\rm{dd}}HCl}} = \dfrac{{9,125}}{{7,3\% }} = 125g\\
c)\\
{n_{NaCl}} = {n_{NaOH}} = 0,25\,mol\\
{m_{{\rm{dd}}spu}} = 50 + 125 = 175g\\
{C_\% }NaCl = \dfrac{{0,25 \times 58,5}}{{175}} \times 100\% = 8,36\%
\end{array}\)