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Câu 4 :
\(n_{H^+}=0.2\cdot0.5\cdot2+0.2\cdot0.25=0.25\left(mol\right)\)
\(H^++OH^-\rightarrow H_2O\)
\(0.25......0.25\)
\(n_{OH^-\left(dư\right)}=0.001V-0.25\left(mol\right)\)
\(C_{M_{OH^-\left(dư\right)}}=\dfrac{0.001V-0.25}{0.2+0.001V}\left(M\right)\)
\(pH=13\)
\(\Rightarrow log\left[OH^-\right]=13-14=-1\)
\(\Rightarrow log\left(\dfrac{0.001V-0.25}{0.2+0.001V}\right)=-1\)
\(\Rightarrow V=300\)
Câu 5 :
\(pH=1\Rightarrow\left[H^+\right]=0.1\)
\(pH=13\Rightarrow\left[OH^-\right]=0.1\)
\(n_{H^+}=0.1V_1\left(mol\right)\)
\(n_{OH^-}=0.1V_2\left(mol\right)\)
\(H^++OH^-\rightarrow H_2O\)
\(0.1V_1...0.1V_1\)
\(n_{OH^-\left(dư\right)}=0.1V_2-0.1V_1\left(mol\right)\)
\(\left[OH^-\right]\left(dư\right)=\dfrac{0.1V_2-0.1V_1}{V_1+V_2}\left(M\right)\)
\(pH=14+log\left[OH^-\right]=12\)
\(\Rightarrow\left[OH^-\right]=0.01\)
\(\Rightarrow\dfrac{0.1V_2-0.1V_1}{V_1+V_2}=0.01\)
\(\Leftrightarrow V_2-V_1-0.1V_1-0.1V_2=0\)
\(\Leftrightarrow0.9V_2-1.1V_1=0\)
\(\Leftrightarrow\dfrac{V_1}{V_2}=\dfrac{0.9}{1.1}=\dfrac{9}{11}\)
Câu 18:
\(n_{NO}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\\ \text{Đ}\text{ặt}:n_{Al}=a\left(mol\right);n_{Fe}=b\left(mol\right)\left(a,b>0\right)\\ Al+4HNO_3\rightarrow Al\left(NO_3\right)_3+NO+2H_2O\\ Fe+4HNO_3\rightarrow Fe\left(NO_3\right)_3+NO+2H_2O\\ \Rightarrow\left\{{}\begin{matrix}a+b=0,15\\27a+56b=5,5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,05\end{matrix}\right.\\ \Rightarrow\%m_{Al}=\dfrac{0,1.27}{5,5}.100\approx49,091\%;\%m_{Fe}\approx50,909\%\\ b,n_{HNO_3}=4.n_{NO}=0,6\left(mol\right)\\ V_{\text{dd}HNO_3}=\dfrac{0,6}{0,3}=2\left(M\right)\)
c) Dung dịch Y là dung dịch nào?
Bài 6:
\(n_{C_2Ag_2}=\dfrac{24}{240}=0,1\left(mol\right)\)
=> nC2H2 = 0,1 (mol)
Khí thoát ra khỏi dd Br2 là C2H6
\(n_{C_2H_6}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
=> \(n_{C_2H_4}=\dfrac{6,72}{22,4}-0,1-0,1=0,1\left(mol\right)\)
\(\left\{{}\begin{matrix}m_{C_2H_2}=0,1.26=2,6\left(g\right)\\m_{C_2H_4}=0,1.28=2,8\left(g\right)\\m_{C_2H_6}=0,1.30=3\left(g\right)\end{matrix}\right.\)
Bài 7:
\(n_{C_3H_3Ag}=\dfrac{22,05}{147}=0,15\left(mol\right)\)
=> nC3H4 = 0,15 (mol)
Khí thoát ra khỏi binh đựng Br2 là C2H6
\(n_{C_2H_6}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
=> \(n_{C_2H_4}=\dfrac{8,96}{22,4}-0,15-0,1=0,15\left(mol\right)\)
\(\left\{{}\begin{matrix}m_{C_2H_4}=0,15.28=4,2\left(g\right)\\m_{C_2H_6}=0,1.30=3\left(g\right)\\m_{C_3H_4}=0,15.40=6\left(g\right)\end{matrix}\right.\)
Câu 24 :
$n_{OH^-\ pư} = n_{H^+} = 0,1.10^{-1} = 0,01(mol)$
$n_{OH^-\ dư} = 0,2.(10^{-14} : 10^{-12}) = 0,002(mol)$
$\Rightarrow n_{OH^-} = 0,01 + 0,002 = 0,012(mol)$
$\Rightarrow a = \dfrac{0,012}{0,1} = 0,12M$
Đáp án D
\(C_4H_{10}\rightarrow C_2H_4\rightarrow C_2H_5OH\)
PT: \(C_4H_{10}\underrightarrow{cracking}C_2H_4+C_2H_6\)
\(C_2H_4+H_2O\rightarrow C_2H_5OH\)