\(\left\{{}\begin{matrix}FeCl_2=0,25\left(mol\right)\\FeCl_3=0,15\left(mol\right)\end{matrix}\right.\underrightarrow{^{NaOH}}\left\{{}\begin{matrix}Fe\left(OH\right)_2\underrightarrow{^{H2O}}\\Fe\left(OH\right)_3\underrightarrow{^{O2}}\end{matrix}\right.\left\{{}\begin{matrix}Fe\left(OH\right)_3\\Fe\left(OH\right)_3\end{matrix}\right.\)
\(\Rightarrow n_{Fe\left(OH\right)3}=0,25+0,15=0,4\left(mol\right)\)
\(\Rightarrow m\downarrow=m_{Fe\left(OH\right)3}=42,8\left(g\right)\)