Đáp án đúng: A
268,2gam.
Thành phần dung dịch Y gồm $\text{F}{{\text{e}}^{\text{3+}}}\text{(1,15}\,\text{mol);}\,\text{C}{{\text{u}}^{\text{2+}}}\text{(0,2}\,\text{mol);}\,\text{C}{{\text{l}}^{\text{-}}}\text{;}\,\text{NO}_{\text{3}}^{\text{-}}$
$\begin{array}{l}\overset{\text{0}}{\mathop{\text{F}{{\text{e}}_{\text{3}}}{{\text{O}}_{\text{4}}}}}\,\xrightarrow{{}}\overset{\text{+3}}{\mathop{\text{Fe}}}\,\text{+}\overset{\text{-2}}{\mathop{\text{O}}}\,\text{+1e}\\\,\,\,\text{0,3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\xrightarrow{{}}\,\,\,\,\,\,\,\,\,\text{0,3}\\\text{Fe}\,\,\xrightarrow{{}}\overset{\text{+3}}{\mathop{\text{Fe}}}\,\,\,\text{+}\,\,\text{3e}\\\text{0,25}\,\,\,\,\,\xrightarrow{{}}\,\,\,\,\,\text{0,75}\end{array}$
$\begin{array}{l}\overset{\text{+5}}{\mathop{\text{N}}}\,\,\text{+}\,\text{3e}\,\xrightarrow{{}}\overset{\text{+2}}{\mathop{\,\text{N}}}\,\\\,\,\,\,\,\,\,\,\text{1,05}\,\to \,\,\,\,\,\text{0,35}\end{array}$
Dung dịch hỗn hợp HCl 3M; HNO3 4M, nhận thấy tỷ lệ nồng độ là tỷ lệ số mol
$\begin{array}{l}\left\{ \begin{array}{l}\text{HCl}\,\,\text{(3a}\,\text{mol)}\\\text{HN}{{\text{O}}_{\text{3}}}\,\,\text{(4a}\,\text{mol)}\end{array} \right.\\\xrightarrow{\text{BTDT}}\sum\limits_{{}}^{{}}{{{\text{n}}_{\text{(C}{{\text{l}}^{\text{-}}}\text{+NO}_{\text{3}}^{\text{-}}\text{)}}}\text{=0,3}\text{.3}\text{.3+0,25}\text{.3+0,2}\text{.2=3,85}}\left\{ \begin{array}{l}\text{C}{{\text{l}}^{\text{-}}}\,\text{(3a)}\\\text{NO}_{\text{3}}^{\text{-}}\,\,\text{(4a-0,35)}\end{array} \right.\\\Rightarrow \text{a=0,6}\Rightarrow \left\{ \begin{array}{l}\text{C}{{\text{l}}^{\text{-}}}\,\text{(1,8)}\\\text{NO}_{\text{3}}^{\text{-}}\,\,\text{(2,05)}\end{array} \right.\end{array}$
mmuối = mKL + manion = 1,15.56 + 0,2.64 +1,8.35,5+2,05.62=268,2 gam
