Giải: Xét \(1\; mol\; Zn\)\(\eqalign{Zn + 2HCl \to ZnC{l_2} + {H_2} \uparrow .\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( 1 \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \cr\;\;1\,\longrightarrow 1\,\,\, \cr
\,\,\,\,\,\,\,\,& \,Zn + 2NaOH + 2{H_2}O \to N{a_2}{\rm{[}}Zn{(OH)_4}{\rm{]}} + {H_2} \uparrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( 2 \right) \cr
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\buildrel {} \over\longrightarrow 1\,\,\,\,\, \cr}\)Từ (1) và (2) ta có : \({n_1} = {n_2} \Rightarrow {V_1} = {V_2}.\)