Có các phản ứng sau: ( 1 )       F e 3 + + 3 H O H ⇌ F e ( O H ) 3 + 3 H + ( 2 )     S 2 − + H 2 O

Có các phản ứng sau:

\begin{array}{l}\text{(}\text{1}\text{)}F{e}^{3+}+3HOH\stackrel{}{\rightleftharpoons }Fe{(OH)}_3+3H^{+}\\ \text{(}\text{2}\text{)}{\text{S}}^{2-}+{\text{H}}_{\text{2}}\text{O}\stackrel{}{\rightleftharpoons }\text{H}{\text{S}}^{-}\text{+}\text{O}{\text{H}}^{-}\\ \text{(}\text{3}\text{)}HC{O}_3^{-}+H_{2}O\stackrel{}{\rightleftharpoons }C{O}_3{}^{2-}+H_3{O}^{+}\\ \text{(}\text{4}\text{)}HC{O}_3^{-}+H_{2}O\stackrel{}{\rightleftharpoons }{H}_{2}C{O}_3+O{H}^{-}\\ \text{(}\text{5}\text{)}\text{H}{\text{S}}^{-}+{\text{H}}_{\text{2}}\text{O}\stackrel{}{\rightleftharpoons }{\text{H}}_2\text{S}\text{+}\text{O}{\text{H}}^{-}\end{array}

Có bao nhiêu ion đóng vai trò base?