Question

Trộn lẫn 3dd HCL 0,05M; H2SO4 0,02M và HNO3 0,06M theo tỉ lệ tương ứng là 1 : 2 : 2 thu được dd có pH là ?

Answer 1

Đặt \(n_{HCl}=a\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}n_{HCl}=a\left(mol\right)\\n_{H_2SO_4}=2a\left(mol\right)\\n_{HNO_3}=2a\left(mol\right)\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}V_{ddHCl}=\dfrac{a}{0,05}\left(l\right)\\V_{ddH_2SO_4}=\dfrac{2a}{0,02}=\dfrac{a}{0,01}\left(l\right)\\V_{ddHNO_3}=\dfrac{2a}{0,06}=\dfrac{a}{0,03}\left(l\right)\end{matrix}\right.\)

\(\Rightarrow n_{H^+}=7a\left(mol\right);V_{dd}=\dfrac{a}{0,05}+\dfrac{a}{0,01}+\dfrac{a}{0,03}=\dfrac{460a}{3}\left(l\right)\)

\(\Rightarrow pH=-log\left(\dfrac{7a}{\dfrac{460a}{3}}\right)=1,34\)