Dùng dung dịch phenolphtalein nhận ra dung dịch KOH.
Các phương trình hoá học :
(1) Mg(NO3)2 + 2KOH \( \to \) \(Mg{(OH)_2} \downarrow + 2KN{O_3}\)
Mg2+ + 2\(O{H^ - }\) \( \to \) \(Mg{(OH)_2} \downarrow \)
(2) Pb(NO3)2 + 2KOH \( \to \) \(Pb{(OH)_2} \downarrow + 2KN{O_3}\)
Pb2+ + 2\(O{H^ - }\) \( \to \) \(Pb{(OH)_2} \downarrow \)
Pb(OH)2 + 2KOH \( \to \) \({K_2}Pb{O_2} + 2{H_2}O\)
Pb(OH)2 + 2\(O{H^ - }\) \( \to \) \(Pb{O_2}^{2 - } + 2{H_2}O\)
(3) Zn(NO3)2 + 2KOH \( \to \) \(Zn{(OH)_2} \downarrow + 2KN{O_3}\)
Zn2+ + 2\(O{H^ - }\) \( \to \) \(Zn{(OH)_2} \downarrow \)
Zn(OH)2 + 2KOH \( \to \) \({K_2}Zn{O_2} + 2{H_2}O\)
Zn(OH)2 + 2\(O{H^ - }\) \( \to \) \(Zn{O_2}^{2 - } + 2{H_2}O\)
(4) AlCl3 + 3KOH \( \to \) \(Al{(OH)_3} \downarrow + 3KCl\)
Al3+ + 3\(O{H^ - }\) \( \to \) \(Al{(OH)_3} \downarrow \)
Al(OH)3 + 3KOH \( \to \) \(KAl{O_2} + 2{H_2}O\)
Al(OH)3 + 3\(O{H^ - }\) \( \to \) \(Al{O_2}^ - + 2{H_2}O\)
(5) 2NaCl + Pb(NO3)2 \( \to \) \(2NaN{O_3} + PbC{l_2} \downarrow \)
Pb2+ + 2\(C{l^ - }\) \( \to \) \(PbC{l_2} \downarrow \)
(6) 3AgNO3 + AlCl3 \( \to \) \(Al{(N{O_3})_3} + 3AgCl \downarrow \)
Ag+ + \(C{l^ - }\) \( \to \) \(AgCl \downarrow \)
