\[\begin{array}{l} + \,\,Ta\"i i\,\,th\^o {\o}i\,\,\~n ie{\aa}m\,\,t\,\,gia\^a y:\,\,{n_{C{l_2}}} = 0,04 \to {n_{elcctron\,\,trao\,\,\~n o{\aa}i}} = 0,08.\\ + \,\,\left\{ \begin{array}{l}Ta\"i i\,\,th\^o {\o}i\,\,\~n ie{\aa}m\,\,2t\,\,gia\^a y\\{n_{elcctron\,\,trao\,\,\~n o{\aa}i}} = 0,08.2 = 0,16\end{array} \right. \to \left\{ \begin{array}{l}{n_{ho\~a n\,\,h\^o \"i p\,\,kh\'i }} = {n_{C{l_2}}} + {n_{{O_2}}} = 0,065\\BTE:\,\,2{n_{C{l_2}}} + 4{n_{{O_2}}} = 0,16\,\end{array} \right. \to \left\{ \begin{array}{l}{n_{C{l_2}}} = 0,05\\{n_{{O_2}}} = 0,015\end{array} \right.\\ + \,\,\left\{ \begin{array}{l}Ta\"i i\,\,th\^o {\o}i\,\,\~n ie{\aa}m\,\,3t\,\,gia\^a y\\{n_{elcctron\,\,trao\,\,\~n o{\aa}i}} = 0,08.3 = 0,24\end{array} \right. \to \left\{ \begin{array}{l}\^O \^U \,\,\,anot:\,\,2\underbrace {{n_{C{l_2}}}}_{0,05} + 4{n_{{O_2}}} = 0,24\\{n_{ho\~a n\,\,h\^o \"i p\,\,kh\'i }} = {n_{{H_2}}} + {n_{C{l_2}}} + {n_{{O_2}}} = 0,11\end{array} \right. \to \left\{ \begin{array}{l}{n_{{O_2}}} = 0,035\\{n_{{H_2}}} = 0,025\end{array} \right.\end{array}\]

 BT e ở catot khi thời gian điện phân là 3t: \({n_{Ag}}.1 + 2.{n_{{H_2}}} = 0,24 \Rightarrow {n_{Ag}} = 0,19\,mol\)

   \(C{\% _{CuC{l_2}}} = \frac{{0,1.135}}{{214,44}}.100 = 6,30\% \)