Đáp án:
a) 36,5g
b) 19,5%
Giải thích các bước giải:
\(\begin{array}{l}
a)\\
mNaOH = C\% \times m{\rm{dd}} = 200 \times 20\% = 40g\\
nNaOH = \dfrac{m}{M} = \dfrac{{40}}{{40}} = 1\,mol\\
NaOH + HCl \to NaCl + {H_2}O\\
nHCl = nNaOH = 1\,mol\\
C\% HCl = \dfrac{{mct}}{{m{\rm{dd}}}} \times 100\% = \dfrac{{1 \times 36,5}}{{100}} \times 100\% = 36,5\% \\
b)\\
m{\rm{dd}}spu = 200 + 100 = 300g\\
nNaCl = nNaOH = 1\,mol\\
C\% NaCl = \dfrac{{1 \times 58,5}}{{300}} \times 100\% = 19,5\%
\end{array}\)