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\(n_{NaOH}=0,2\left(mol\right);n_{H_2SO_4}=0,2\left(mol\right)\)
\(\Rightarrow n_{OH^-}=0,2\left(mol\right);n_{H^+}=0,4\left(mol\right)\)
\(H^++OH^-\rightarrow H_2O\)
0,4......0,2
Lập tỉ lệ : \(\dfrac{0,4}{1}>\dfrac{0,2}{2}\)
=> H+ dư sau phản ứng
Dung dịch X gồm các ion:
Na+ : 0,2(mol)
SO42- : 0,2 (mol)
H+ dư : 0,2mol
=> \(\left[Na^+\right]=\dfrac{0,2}{0,4}=0,5M\)
\(\left[SO_4^{2-}\right]=\dfrac{0,2}{0,4}=0,5M\)
\(\left[H^+\right]=\dfrac{0,2}{0,4}=0,5M\)
$n_{NaOH} = 0,2(mol) ; n_{H_2SO_4} = 0,2(mol)$
$2NaOH + H_2SO_4 \to Na_2SO_4 + 2H_2O$
$n_{NaOH} : 2 < n_{H_2SO_4} : 1$ nên $H_2SO_4$ dư
$n_{Na_2SO_4} = n_{H_2SO_4\ pư} = \dfrac{1}{2}n_{NaOH} = 0,1(mol)$
$V_{dd} = 0,2 + 0,2 = 0,4(lít)$
$C_{M_{Na_2SO_4}} = \dfrac{0,1}{0,4} = 0,25M$
$C_{M_{H_2SO_4\ dư}} = \dfrac{0,2-0,1}{0,4} = 0,25M$
Suy ra :
$[Na^+] = 0,25.2 = 0,5M$
$[H^+] = 0,25.2 = 0,5M$
$[SO_4^{2-}] = 0,25 + 0,25 = 0,5M$
\(n_{ }_{NAOH}=0.2.1=0.2mol\)
\(n_{H_2sõ_4}=0.2.2=0.4mol\)
\(OH^-+H^+\rightarrow H_20\)
0.2 0.8
\(NAOH\rightarrow Na^++OH^-\)
0.2 0.2
\(H_2SO_4\rightarrow2H^++SO^{2-}_4\)
0.4 0.4
\(\left[Na^+\right]=\frac{0.2}{0.4}=0.5M\)
\(\left[SO^{2-}_4\right]=\frac{0.4}{0.4}=1M\)
\(\left[H^+_{dư}\right]=\frac{0,6}{0,4}=1.5M\)
\(a.n_{NaCl}=0,2.2=0,4\left(mol\right)\\ n_{CaCl_2}=0,5.0,2=0,1\left(mol\right)\\ \left[Na^+\right]=\left[NaCl\right]=\dfrac{0,4.1}{0,2+0,2}=1\left(M\right)\\ \left[Ca^{2+}\right]=\left[CaCl_2\right]=\dfrac{0,1.1}{0,2+0,2}=0,25\left(M\right)\\ \left[Cl^-\right]=1.1+0,25.2=1,5\left(M\right)\)
\(b.\\ n_{MgSO_4}=\dfrac{12}{120}=0,1\left(mol\right)\\ n_{Al_2\left(SO_4\right)_3}=\dfrac{34,2}{342}=0,1\left(mol\right)\\ \left[Mg^{2+}\right]=\left[MgSO_4\right]=\dfrac{0,1}{0,2+0,3}=0,2\left(M\right)\\ \left[Al^{3+}\right]=2.\left[Al_2\left(SO_4\right)_3\right]=2.\dfrac{0,1}{0,2+0,3}=0,4\left(M\right)\\ \left[SO^{2-}_4\right]=0,2.1+0,2.3=0,8\left(M\right)\)
\(C_6H_5OH + NaOH \to C_6H_5ONa + H_2O\\ n_{C_6H_5OH} = 0,2.0,3 = 0,06(mol)\\ n_{H_2} = \dfrac{0,896}{22,4} = 0,04(mol)\\ 2C_6H_5OH + 2Na \to 2C_6H_5ONa + H_2\\ 2C_2H_5OH + 2Na \to 2C_2H_5ONa + H_2\\ 2n_{H_2} = n_{C_6H_5OH} + n_{C_2H_5OH}\\ \Rightarrow n_{C_2H_5OH} = 0,04.2 - 0,06 = 0,02(mol)\\ \Rightarrow m = 0,06.94 + 0,02.46 = 6,56(gam)\)
PT ion: \(H^++OH^-\rightarrow H_2O\)
Ta có: \(\left\{{}\begin{matrix}n_{H^+}=0,2\cdot0,5\cdot2=0,2\left(mol\right)\\n_{OH^-}=0,05\cdot2=0,1\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\) H+ còn dư 0,1 mol
\(\Rightarrow\left[H^+\right]=\dfrac{0,1}{0,25}=0,4\left(M\right)\) \(\Rightarrow pH=-log\left(0,4\right)\approx0,4\)
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.
\(n_{H^+}=n_{Cl^-}=2.0,15=0,3\left(mol\right)\Rightarrow\left[Cl^-\right]=\left[H^+\right]=\dfrac{0,3}{0,15+0,05}=1,5M\)
\(n_{Ba^{2+}}=0,05.2,8=0,14\left(mol\right)\Rightarrow\left[Ba^{2+}\right]=\dfrac{0,14}{0,15+0,05}=0,7M\)
\(n_{OH^-}=2.0,05.2,8=0,28\left(mol\right)\Rightarrow\left[OH^-\right]=\dfrac{0,28}{0,15+0,05}=1,4M\)
Ta có: \(n_{Na^+}=n_{OH^-}=n_{NaOH}=0,2.1=0,2\left(mol\right)\)
\(n_{SO_4^{2-}}=n_{H_2SO_4}=0,2.2=0,4\left(mol\right)\)
\(n_{H^+}=2n_{H_2SO_4}=0,8\left(mol\right)\)
\(H^++OH^-\rightarrow H_2O\)
0,2 ← 0,2 _________ (mol)
\(\Rightarrow n_{H^+\left(dư\right)}=0,6\left(mol\right)\)
Dung dịch thu được gồm: Na+, SO42- và H+
\(\Rightarrow\left\{{}\begin{matrix}\left[Na^+\right]=\frac{0,2}{0,4}=0,5M\\\left[SO_4^{2-}\right]=\frac{0,4}{0,4}=1M\\\left[H^+\right]=\frac{0,6}{0,4}=1,5M\end{matrix}\right.\)
Bạn tham khảo nhé!