Đáp án:
${m_{MOH}} = 4,8\,\,gam$
Giải thích các bước giải:
Gọi công thức chung của hai kim loại kiềm là $M$
PTHH:
$\begin{gathered} M + {H_2}O \to MOH + \frac{1}{2}{H_2}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \hfill \\ \,\,\,\,\,\,\,\,\,\,\,\,\,0,1\,\,\,\,\,\,\,\,\, \leftarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0,05\,\,\,\,\,\,\,\,\,\,\,\,\,mol \hfill \\ \end{gathered} $
Bảo toàn khối lượng:
$\begin{gathered} \,\,\,\,\,\,{m_M} + {m_{{H_2}O}} = {m_{MOH}} + {m_{{H_2}}}\,\,\,\,\, \hfill \\ \to 3,1 + 0,1.18 = {m_{MOH}} + 0,05.2 \hfill \\ \to \,\,\,\,\,\,\,\,\,\,\,\,\,\,{m_{MOH}} = 4,8\,\,gam\,\,\,\,\,\,\,\,\,\,\,\,\, \hfill \\ \end{gathered} $
