Đáp án đúng: D
15
$\displaystyle {{M}_{Z}}=5\Rightarrow $ có khí H2$\displaystyle \Rightarrow \left\{ \begin{array}{l}{{n}_{NO}}=0,025\\{{n}_{{{H}_{2}}}}=0,2\end{array} \right.\,\,\,;\,\,\,{{m}_{Z}}=1,15\,gam$
+) BTKL:$\displaystyle 33,1-1,55.1,36=233,3+0,225.469+{{m}_{{{H}_{2}}\text{O}}}$
$\displaystyle \Rightarrow {{n}_{{{H}_{2}}\text{O}}}=9,45\Rightarrow {{n}_{{{H}_{2}}\text{O}}}=0,525\,mol$
+) Đặt$\displaystyle {{n}_{N{{H}_{4}}^{+}}}=x$⟹ 1,55 = 4x + 2.0,525 + 2.0,2
⟹ x = 0,025 mol (Bảo toàn Hidro)
$\displaystyle \Rightarrow {{n}_{NO_{3}^{-}}}=0,025+0,025=0,05\Rightarrow {{n}_{{{\left( F\text{e}N{{\text{O}}_{3}} \right)}_{2}}}}=0,025\,\,mol$
+) Đặt$\displaystyle {{\text{n}}_{\text{F}{{\text{e}}_{\text{3}}}{{\text{O}}_{\text{4}}}}}\text{= a}$
Bảo toàn oxi: 4a + 0,025.6 = 0,525 + 0,025 ⟹ a = 0,1 mol
⟹ mAl = 33,1 – 0,1.232 – 180.0,025 = 5,4 gam
⟹ %mAl = 16,31%