a, - Hiện tượng: Xuất hiện kết tủa trắng.
b, PT: \(Al_2\left(SO_4\right)_3+3BaCl_2\rightarrow2AlCl_3+3BaSO_{4\downarrow}\)
\(n_{Al_2\left(SO_4\right)_3}=0,3.0,2=0,06\left(mol\right)\)
Theo PT: \(\left\{{}\begin{matrix}n_{AlCl_3}=2n_{Al_2\left(SO_4\right)_3}=0,12\left(mol\right)\\n_{BaSO_4}=3n_{Al_2\left(SO_4\right)_3}=0,18\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{AlCl_3}=0,12.133,5=16,02\left(g\right)\\m_{BaSO_4}=0,18.233=41,94\left(g\right)\end{matrix}\right.\)