Em tham khảo nha :
\(\begin{array}{l}
18)\\
C\\
2Fe{(OH)_3} + 3{H_2}S{O_4} \to F{e_2}{(S{O_4})_3} + 6{H_2}O\\
{n_{Fe{{(OH)}_3}}} = \dfrac{{10,7}}{{107}} = 0,1mol\\
{m_{{H_2}S{O_4}}} = \dfrac{{200 \times 9,8}}{{100}} = 19,6g\\
{n_{{H_2}S{O_4}}} = \dfrac{{19,6}}{{98}} = 0,2mol\\
\dfrac{{0,1}}{2} < \dfrac{{0,2}}{3} \Rightarrow {H_2}S{O_4}\text{ dư}\\
{n_{F{e_2}{{(S{O_4})}_3}}} = \dfrac{{{n_{Fe{{(OH)}_3}}}}}{2} = 0,05mol\\
{m_{F{e_2}{{(S{O_4})}_3}}} = 0,05 \times 400 = 20g\\
19)\\
D\\
A{l_2}{O_3} + 6HCl \to 2AlC{l_3} + 3{H_2}O\\
{n_{A{l_2}{O_3}}} = \dfrac{{10,2}}{{102}} = 0,1mol\\
{n_{HCl}} = 0,15 \times 2 = 0,3mol\\
\dfrac{{0,1}}{1} > \dfrac{{0,3}}{6} \Rightarrow A{l_2}{O_3}\text{ dư}\\
{n_{AlC{l_3}}} = \dfrac{{{n_{HCl}}}}{3} = 0,1mol\\
{m_{AlC{l_3}}} = 0,1 \times 133,5 = 13,35g
\end{array}\)
