Question

1. Cho 300ml dd KOH 0,6M vào 200ml dd AlCl3 1,2M , sau pư thu đc m gam kết tủa. Giá trị m là?

2. Cho 200ml dd Al2(SO4)3 1M vào 400ml dd NaOH 1,75M. Sau pư thu đc m gam kết tủa , giá trị m là?

Answer 1

1/ \(n_{KOH}=0,6.0,3=0,18\left(mol\right);n_{AlCl_3}=1,2.0,2=0,24\left(mol\right)\)

\(\Rightarrow n_{OH^-}=0,18\left(mol\right);n_{Al^{3+}}=0,24\left(mol\right)\)

\(Al^{3+}+3OH^-\rightarrow Al\left(OH\right)_3\)

\(0,06\leftarrow0,18\rightarrow0,06\)

\(\Rightarrow m_{Al\left(OH\right)_3}=0,06.78=4,68\left(g\right)\)

2/ \(n_{Al_2\left(SO_4\right)_3}=0,2\left(mol\right);n_{NaOH}=1,75.0,4=0,7\left(mol\right)\)

\(Al_2\left(SO_4\right)_3\rightarrow2Al^{3+}+3SO_4^{2-}\)

\(0,2---\rightarrow0,4---\rightarrow0,6\)

\(Al^{3+}+3OH^-\rightarrow Al\left(OH\right)_3\)

\(0,4--\rightarrow1,2--\rightarrow0,4\)

\(\Rightarrow m_{Al\left(OH\right)_3}=0,4.78=31,2\left(g\right)\)