\(m_{NaOH}=200\cdot20\%=40\left(g\right)\)
\(\Rightarrow n_{NaOH}=0,1\left(mol\right)\)
mdd ( sau pư) = 200 + 100 = 300 (g)
NaOH+HCl => NaCl+H2O
1mol=>1mol=>1mol
\(\Rightarrow C\%_{dd}NaCl=\frac{58,5}{100}\times100\%=19,5\%\)
\(m_{HCl}=36,5\left(g\right)\)
\(\Rightarrow C\%_{dd}HCl=\frac{36,5}{100}\cdot100\%=36,5\%\)