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\(a,n_{H_2}=\dfrac{7,437}{24,79}=0,3(mol)\\ PTHH:Mg+2HCl\to MgCl_2+H_2\\ \Rightarrow n_{HCl}=2n_{H_2}=0,6(mol)\\ \Rightarrow m_{CT_{HCl}}=0,6.36,5=21,9(g)\\ \Rightarrow m_{dd_{HCl}}=\dfrac{21,9}{28\%}=78,21(g)\\ b,n_{Mg}=n_{H_2}=0,3(mol)\\ \Rightarrow m_{Mg}=0,3.24=7,2(g)\\ \Rightarrow {\%}_{Mg}=\dfrac{7,2}{18}.100{\%}=40\%\\ \Rightarrow {\%}_{Ag}=60\%\)
a/ \(n_{H_2}=\dfrac{7,437}{24,79}=0,3\left(mol\right)\)
PTHH: Mg + 2HCl → MgCl2 + H2
Mol: 0,3 0,6 0,3 0,3
\(m_{Mg}=0,3.24=7,2\left(g\right)\)
b/ \(m_{MgCl_2}=0,3.95=28,5\left(g\right)\)
c/ \(m_{HCl}=0,3.36,5=10,95\left(g\right)\)
PTHH: \(CH_3COOH+KHCO_3\rightarrow CH_3COOK+H_2O+CO_2\uparrow\)
a) Ta có: \(n_{CH_3COOH}=\dfrac{200\cdot24\%}{60}=0,8\left(mol\right)=n_{KHCO_3}\)
\(\Rightarrow m_{ddKHCO_3}=\dfrac{0,8\cdot100}{16,8\%}\approx476.2\left(g\right)\)
b) Theo PTHH: \(n_{CH_3COOK}=0,8\left(mol\right)=n_{CO_2}\)
\(\Rightarrow\left\{{}\begin{matrix}m_{CH_3COOK}=0,8\cdot98=78,4\left(g\right)\\m_{CO_2}=0,8\cdot44=35,2\left(g\right)\end{matrix}\right.\)
Mặt khác: \(m_{dd}=m_{ddCH_3COOH}+m_{ddKHCO_3}-m_{CO_2}=641\left(g\right)\)
\(\Rightarrow C\%_{CH_3COOK}=\dfrac{78,4}{641}\cdot100\%\approx12,23\%\)
Bài 8:
\(n_{H_2}=\dfrac{7,437}{24,79}=0,3\left(mol\right)\)
PT: \(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
_____0,2______0,6_____0,2____0,3 (mol)
a, \(m_{Al}=0,2.27=5,4\left(g\right)\)
b, \(C_{M_{HCl}}=\dfrac{0,6}{0,3}=2\left(M\right)\)
c, \(C_{M_{AlCl_3}}=\dfrac{0,2}{0,2}=1\left(M\right)\)
Bài 9:
Ta có: \(n_{H_2}=\dfrac{2,479}{24,79}=0,1\left(mol\right)\)
PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(MgO+2HCl\rightarrow MgCl_2+H_2O\)
a, \(n_{Mg}=n_{H_2}=0,1\left(mol\right)\Rightarrow m_{Mg}=0,1.24=2,4\left(g\right)\)
\(\Rightarrow m_{MgO}=8,4-2,4=6\left(g\right)\)
b, \(n_{MgO}=\dfrac{6}{40}=0,15\left(mol\right)\)
Theo PT: \(n_{HCl}=2n_{Mg}+2n_{MgO}=0,5\left(mol\right)\)
\(\Rightarrow m_{ddHCl}=\dfrac{0,5.36,5}{3,65\%}==500\left(g\right)\)
Ta có: \(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)
PT: \(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)
a, \(n_{Al}=\dfrac{2}{3}n_{H_2}=\dfrac{1}{6}\left(mol\right)\Rightarrow m_{Al}=\dfrac{1}{6}.27=4,5\left(g\right)\)
b, \(n_{H_2SO_4}=n_{H_2}=0,25\left(mol\right)\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,25}{0,2}=1,25\left(M\right)\)
c, \(n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{3}n_{H_2}=\dfrac{1}{12}\left(mol\right)\)
\(\Rightarrow m_{Al_2\left(SO_4\right)_3}=\dfrac{1}{12}.342=28,5\left(g\right)\)
a, \(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)
\(n_{H_2}=\dfrac{7,437}{24,79}=0,3\left(mol\right)\)
Theo PT: \(n_{Fe}=n_{H_2}=0,3\left(mol\right)\Rightarrow m_{Fe}=0,3.56=16,8\left(g\right)\)
b, \(n_{H_2SO_4}=n_{H_2}=0,3\left(mol\right)\Rightarrow C\%_{H_2SO_4}=\dfrac{0,3.98}{120}.100\%=24,5\%\)
c, m dd sau pư = 16,8 + 120 - 0,3.2 = 136,2 (g)
d, \(n_{FeSO_4}=n_{H_2}=0,3\left(mol\right)\)
\(\Rightarrow C\%_{FeSO_4}=\dfrac{0,3.152}{136,2}.100\%\approx33,48\%\)
$n_{NaOH} = \dfrac{50.10\%}{40} = 0,125(mol)$
$CH_3COOH + NaOH \to CH_3COONa + H_2O$
Theo PTHH :
$n_{CH_3COOH} = n_{CH_3COONa} = n_{NaOH} = 0,125(mol)$
$m_{dd\ CH_3COOH} = \dfrac{0,125.60}{8\%} = 93,75(gam)$
$m_{dd\ sau\ pư} = m_{dd\ CH_3COOH} + m_{dd\ NaOH} = 143,75(gam)$
$C\%_{CH_3COONa} = \dfrac{0,125.82}{143,75}.100\% = 7,13\%$
Ta có: \(n_{Fe_3O_4}=\dfrac{2,32}{232}=0,01\left(mol\right)\)
a. PTHH: Fe3O4 + 4H2SO4 ---> FeSO4 + Fe2(SO4)3 + 4H2O
Theo PT: \(n_{H_2SO_4}=4.n_{Fe_3O_4}=4.0,01=0,04\left(mol\right)\)
=> \(m_{H_2SO_4}=0,04.98=3,92\left(g\right)\)
Theo đề, ta có: \(C_{\%_{H_2SO_4}}=\dfrac{3,92}{m_{dd_{H_2SO_4}}}.100\%=20\%\)
=> \(m_{dd_{H_2SO_4}}=19,6\left(g\right)\)
b. Ta có: \(m_{dd_{SauPỨ}}=2,32+19,6=21,92\left(g\right)\)
Theo PT: \(n_{FeSO_4}=n_{Fe_2\left(SO_4\right)_3}=n_{Fe_3O_4}=0,01\left(mol\right)\)
=> \(m_{FeSO_4}=0,01.152=1,52\left(g\right)\)
\(m_{Fe_2\left(SO_4\right)_3}=0,01.400=4\left(g\right)\)
=> \(m_{SauPỨ}=1,52+4=5,52\left(g\right)\)
=> \(C_{\%_{SauPỨ}}=\dfrac{5,52}{21,92}.100\%=25,18\%\)
a) \(n_{\left(CH_3COO\right)_2Mg}=\dfrac{7,1}{142}=0,05\left(mol\right)\)
PTHH: 2CH3COOH + Mg --> (CH3COO)2Mg + H2
0,1<----------------------0,05------->0,05
=> VH2 = 0,05.22,4 = 1,12 (l)
b) \(C_{M\left(dd.CH_3COOH\right)}=\dfrac{0,1}{0,025}=4M\)
\(2CH_3COOH+Zn\rightarrow\left(CH_3COO\right)_2Zn+H_2\\ n_{H_2}=\dfrac{7,437}{24,79}=0,3\left(mol\right)\\ a,n_{CH_3COOH}=2.n_{H_2}=2.0,3=0,6\left(mol\right)\\ m_{ddCH_3COOH}=\dfrac{0,6.60.100}{20}=180\left(g\right)\\ b,n_{\left(CH_3COO\right)_2Zn}=n_{Zn}=n_{H_2}=0,3\left(mol\right)\\ C\%_{dd\left(CH_3COO\right)_2Zn}=\dfrac{0,3.183}{180+0,3.65-0,3.2}.100\approx27,602\%\)