\(Hoà tan 2,61 g Ba (NO3) vào nước được 200ml tính N độ mol các ion trong dung dịch\)
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Đổi \(200ml=0,2l\)
Số mol của 5,85g NaCl là:
\(n_{NaCl}=\dfrac{m_{NaCl}}{M_{NaCl}}=\dfrac{5,85}{58,5}=0,1\left(mol\right)\)
Nồng độ mol của \(5,85g\) \(NaCl\) là:
\(C_MNaCl=\dfrac{n}{V}=\dfrac{0,1}{0,2}=0,5\left(M\right)\)
\(n_{NaNO_3}=\dfrac{3,4}{85}=0,04\left(mol\right)\\ n_{Ba\left(NO_3\right)_2}=\dfrac{5,22}{261}=0,02\left(mol\right)\\ \left[Na^+\right]=\left[NaNO_3\right]=\dfrac{0,04}{0,5}=0,08\left(M\right)\\ \left[Ba^{2+}\right]=\left[Ba\left(NO_3\right)_2\right]=\dfrac{0,02}{0,5}=0,04\left(M\right)\\ \left[NO^-_3\right]=0,08+0,04.2=0,16\left(M\right)\)
\(n_{NaCl}=\dfrac{1,17}{58,5}=0,02\left(mol\right)\\ n_{BaCl_2}=\dfrac{2,08}{208}=0,01\left(mol\right)\\ \left[Na^+\right]=\dfrac{0,02}{0,1}=0,2\left(M\right)\\ \left[Ba^{2+}\right]=\dfrac{0,01}{0,1}=0,1\left(M\right)\\ \left[Cl^-\right]=\dfrac{0,02+0,01.2}{0,1}=0,4\left(M\right)\)
a) 200ml=0,2(l)
Ta có: \(n_{KOH}=\dfrac{m}{M}=\dfrac{28}{56}=0,5\left(mol\right)\)
\(\Rightarrow C_{M_{KOH}}=\dfrac{n}{V}=\dfrac{0,5}{0,2}=2,5\left(M\right)\)
b) 1500ml=1,5(l)
\(C_{M_{Na_2CO_3}}=\dfrac{n}{V}=\dfrac{0,06}{1,5}=0,04\left(M\right)\)
\(n_{OH^-}=n_{NaOH}=0,3.1,5=0,45\left(mol\right)\\ n_{H^+}=n_{HCl}+2n_{H_2SO_4}=0,2x+0,5.0,2.2=0,2x+0,2\left(mol\right)\)
PT ion rút gọn: \(H^++OH^-\rightarrow H_2O\)
0,45<---0,45
\(\Rightarrow0,2x+0,2=0,45\Leftrightarrow x=1,25M\)
Ta có: \(V_{dd}=0,3+0,2=0,5\left(l\right)\) và \(\left\{{}\begin{matrix}n_{Na^+}=0,45\left(mol\right)\\n_{Cl^-}=0,2.1,25=0,25\left(mol\right)\\n_{SO_4^{2-}}=0,2.0,5=0,1\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}C_{Na^+}=\dfrac{0,45}{0,5}=0,9M\\C_{Cl^-}=\dfrac{0,25}{0,5}=0,5M\\C_{SO_4^{2-}}=\dfrac{0,1}{0,5}=0,2M\end{matrix}\right.\)
1)
$n_{Na_2O} = \dfrac{6,2}{62} = 0,1(mol)$
$Na_2O + H_2O \to 2NaOH$
$n_{NaOH} = 2n_{Na_2O} = 0,2(mol)$
$m_{dd} = 6,2 + 193,8 = 200(gam) \Rightarrow C\%_{NaOH} = \dfrac{0,2.40}{200}.100\% = 4\%$
2)
$n_{K_2O} = \dfrac{23,5}{94} = 0,25(mol)$
$K_2O + H_2O \to 2KOH$
$n_{KOH} = 2n_{K_2O} = 0,5(mol) \Rightarrow C_{M_{KOH}} = \dfrac{0,5}{0,5} = 1M$
3) $n_{Na_2O} = \dfrac{12,4}{62} = 0,2(mol)$
$Na_2O + H_2O \to 2NaOH$
$n_{NaOH} = 2n_{Na_2O} = 0,4(mol)$
$C_{M_{NaOH}} = \dfrac{0,4}{0,5} =0,8M$
4)
$Na_2SO_3 + 2HCl \to 2NaCl +S O_2 + H_2O$
Theo PTHH :
$n_{SO_2} = n_{Na_2SO_3} = \dfrac{12,6}{126} = 0,1(mol)$
$V_{SO_2} = 0,1.22,4 = 2,24(lít)$
5) $n_{CaO} = \dfrac{5,6}{56} = 0,1(mol)$
$CaO + 2HCl \to CaCl_2 + H_2O$
Theo PTHH :
$n_{HCl} = 2n_{CaO} = 0,2(mol) \Rightarrow m_{dd\ HCl} = \dfrac{0,2.36,5}{14,6\%} = 50(gam)$
PT: \(2K+2H_2O\rightarrow2KOH+H_2\)
\(Ba+2H_2O\rightarrow Ba\left(OH\right)_2+H_2\)
a, Giả sử: \(\left\{{}\begin{matrix}n_K=x\left(mol\right)\\n_{Ba}=y\left(mol\right)\end{matrix}\right.\)
⇒ 39x + 137y = 21,5 (1)
Ta có: \(n_{H_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)
Theo PT: \(n_{H_2}=\dfrac{1}{2}n_K+n_{Ba}=\dfrac{1}{2}x+y\left(mol\right)\)
\(\Rightarrow\dfrac{1}{2}x+y=0,2\left(2\right)\)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,2\left(mol\right)\\y=0,1\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\%m_K=\dfrac{0,2.39}{21,5}.100\%\approx36,28\%\)
b, Theo PT: \(\left\{{}\begin{matrix}n_{KOH}=n_K=0,2\left(mol\right)\\n_{Ba\left(OH\right)_2}=n_{Ba}=0,1\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}C_{M_{KOH}}=\dfrac{0,2}{0,2}=1M\\C_{M_{Ba\left(OH\right)_2}}=\dfrac{0,1}{0,2}=0,5M\end{matrix}\right.\)
c, Ta có: \(n_{OH}=n_{KOH}+2n_{Ba\left(OH\right)_2}=0,4\left(mol\right)\)
Bạn tham khảo nhé!