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a, \(\left\{{}\begin{matrix}n_{Ba^{2+}}=4.10^{-3}\left(mol\right)\\n_{Na^+}=3.10^{-3}\left(mol\right)\\n_{OH^-}=0,011\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\left[Ba^{2+}\right]=\dfrac{4.10^{-3}}{0,2+0,3}=0,008M\\\left[Na^+\right]=\dfrac{3.10^{-3}}{0,2+0,3}=0,006M\\\left[OH^-\right]=\dfrac{0,011}{0,2+0,3}=0,022M\end{matrix}\right.\)
b, Để trung hòa dung dịch A thì:
\(n_{H^+}=n_{OH^-}\)
\(\Leftrightarrow0,01.V_{ddHCl}=\left(0,02.2+0,01\right).0,2\)
\(\Leftrightarrow V_{ddHCl}=1\left(l\right)\)
3.
\(n_{Ba^{2+}}=0,5.0,2=0,1\left(mol\right)\Rightarrow\left[Ba^{2+}\right]=\dfrac{0,1}{0,2+0,4}=0,17M\)
\(n_{Cl^-}=2.0,5.0,2=0,2\left(mol\right)\Rightarrow\left[Cl^-\right]=\dfrac{0,2}{0,2+0,4}=0,33M\)
\(n_{Na^+}=2.0,2.0,4=0,16\left(mol\right)\Rightarrow\left[Na^+\right]=\dfrac{0,16}{0,2+0,4}=0,27M\)
\(n_{SO_4^{2-}}=0,2.0,4=0,08\left(mol\right)\Rightarrow\left[SO_4^{2-}\right]=\dfrac{0,08}{0,2+0,4}=0,13M\)
4.
\(n_{H^+}=n_{Cl^-}=2.0,15=0,3\left(mol\right)\Rightarrow\left[Cl^-\right]=\left[H^+\right]=\dfrac{0,3}{0,15+0,05}=1,5M\)
\(n_{Ba^{2+}}=0,05.2,8=0,14\left(mol\right)\Rightarrow\left[Ba^{2+}\right]=\dfrac{0,14}{0,15+0,05}=0,7M\)
\(n_{OH^-}=2.0,05.2,8=0,28\left(mol\right)\Rightarrow\left[OH^-\right]=\dfrac{0,28}{0,15+0,05}=1,4M\)
Câu 1:
PT ion: \(H^++OH^-\rightarrow H_2O\)
Ta có: \(\left\{{}\begin{matrix}n_{OH^-}=0,6\cdot0,4+0,6\cdot0,3\cdot2=0,6\left(mol\right)\\n_{H^+}=0,2\cdot2,6=0,52\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\) H+ hết, OH- còn dư \(\Rightarrow n_{OH^-\left(dư\right)}=0,08\left(mol\right)\)
\(\Rightarrow\left[OH^-\right]=\dfrac{0,08}{0,6+0,2}=0,1\left(M\right)\) \(\Rightarrow pH=14+log\left(0,1\right)=13\)
Bài 2:
PT ion: \(H^++OH^-\rightarrow H_2O\)
Ta có: \(\left\{{}\begin{matrix}n_{OH^-}=0,3\cdot1,6=0,48\left(mol\right)\\n_{H^+}=0,2\cdot1\cdot2+0,2\cdot2=0,8\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\) OH- hết, H+ còn dư \(\Rightarrow n_{H^+\left(dư\right)}=0,32\left(mol\right)\)
\(\Rightarrow\left[H^+\right]=\dfrac{0,32}{0,2+0,3}=0,64\left(M\right)\) \(\Rightarrow pH=-log\left(0,64\right)\approx0,19\)
Mong mn giúp mình hướng dẫn cách giải ạ,tks mn