Cần thêm ít nhất bao nhiêu ml dung dịch Na2CO3 0,15M vào 25ml dung dịch Al2(SO4)3 0,02M để làm kết tủa hoàn toàn ion nhôm? A. 15 ml. B. 10 ml. C. 30 ml. D. 12 ml.
Đáp án đúng: B 10 ml. $\begin{array}{l}\text{2A}{{\text{l}}^{\text{3+}}}\,\,\,\,\text{+}\,\,\,\,\text{3CO}_{\text{3}}^{\text{2-}}\,\text{+3}{{\text{H}}_{\text{2}}}\text{O}\,\xrightarrow{{}}\,2\text{Al(OH}{{\text{)}}_{\text{3}}}\,\text{+}\,3\text{C}{{\text{O}}_{\text{2}}}\uparrow \\\text{1}{{\text{0}}^{\text{-3}}}\,\xrightarrow{{}}\,\text{1,5}\text{.1}{{\text{0}}^{\text{-3}}}\\\Rightarrow \,{{\text{V}}_{\text{N}{{\text{a}}_{\text{2}}}\text{C}{{\text{O}}_{\text{3}}}}}\,\text{=}\,\frac{\text{1,5}\text{.1}{{\text{0}}^{\text{-3}}}}{\text{0,15}}\,\text{=}\,\text{0,01}\,\text{lit}\end{array}$
