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\(n_{Fe_2O_3}=\dfrac{8}{160}=0,05\left(mol\right)\)
PTHH: Fe2O3 + 3H2SO4 --> Fe2(SO4)3 + 3H2O
______0,05------>0,15--------->0,05
=> mH2SO4 = 0,15.98 = 14,7(g)
=> \(C\%\left(H_2SO_4\right)=\dfrac{14,7}{100}.100\%=14,7\%\)
\(C\%\left(Fe_2\left(SO_4\right)_3\right)=\dfrac{0,05.400}{8+100}.100\%=18,52\%\)
PTHH: Fe2(SO4)3 + 6NaOH --> 2Fe(OH)3\(\downarrow\) + 3Na2SO4
________0,05----------------------->0,1
=> mFe(OH)3 = 0,1.107=10,7(g)
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: \(m_{dd}=m_{ddCH_3COOH}+m_{ddKHCO_3}-m_{CO_2}=641\left(g\right)\)
\(\Rightarrow C\%_{CH_3COOK}=\dfrac{78,4}{641}\cdot100\%\approx12,23\%\)
\(m_{CH_3COOH}=24\%.150=36\left(g\right)\\ \rightarrow n_{CH_3COOH}=\dfrac{36}{60}=0,6\left(mol\right)\)
PTHH: 2CH3COOH + Na2CO3 ---> 2CH3COONa + CO2 + H2O
0,6 0,3 0,6 0,3
=> VCO2 = 0,3.22,4 = 6,72 (l)
\(m_{Na_2CO_3}=0,3.31,8\left(g\right)\)
=> \(m_{ddNa_2CO_3}=\dfrac{31,8}{21,2\%}=150\left(g\right)\)
mCO2 = 0,3.44 = 13,2 (g)
\(m_{dd}=150+150-13,2=286,8\left(g\right)\)
\(m_{CH_3COONa}=0,3.82=24,6\left(g\right)\\ \rightarrow C\%_{CH_3COONa}=\dfrac{24,6}{286,8}=8,58\%\)
\(n_{CH_3COOH}=\dfrac{100.12\%}{60}=0,2\left(mol\right)\)
PTHH: CH3COOH + NaHCO3 --> CH3COONa + CO2 + H2O
0,2------>0,2-------------->0,2------->0,2
=> \(m_{dd.NaHCO_3.8,4\%}=\dfrac{0,2.84.100}{8,4}=200\left(g\right)\)
mdd sau pư = 100 + 200 - 0,2.44 = 291,2 (g)
\(m_{CH_3COONa}=0,2.82=16,4\left(g\right)\)
=> \(C\%_{CH_3COONa}=\dfrac{16,4}{291,2}.100\%=5,632\%\)
a) $n_{Fe} = \dfrac{11,2}{56} = 0,2(mol)$
$Fe + 2HCl \to FeCl_2 + H_2$
$n_{HCl} =2 n_{Fe} = 0,2.2 = 0,4(mol)$
$C\%_{HCl} = \dfrac{0,4.36,5}{200}.100\% = 7,3\%$
b) $n_{H_2} = n_{FeCl_2} = n_{Fe} = 0,2(mol)
Sau phản ứng, $m_{dd} = 11,2 + 200 - 0,2.2 = 210,8(gam)$
$C\%_{FeCl_2} = \dfrac{0,2.127}{210,8}.100\% = 12,05\%$
a) Na2CO3 + 2CH3COOH --> 2CH3COONa + CO2 + H2O
b) \(n_{CH_3COOH}=\dfrac{25.6\%}{60}=0,025\left(mol\right)\)
PTHH: Na2CO3 + 2CH3COOH --> 2CH3COONa + CO2 + H2O
0,0125<-----0,025------------>0,025------>0,0125
=> \(m_{Na_2CO_3}=0,0125.106=1,325\left(g\right)\)
c) \(m_{dd.sau.pư}=1,325+25-0,0125.44=25,775\left(g\right)\)
\(C\%_{dd.CH_3COONa}=\dfrac{0,025.82}{25,775}.100\%=7,95\%\)
Mg+2CH3COOH->(CH3COO)2Mg+H2
0,15------0,3-------------0,15-------------0,15
n Mg=\(\dfrac{3,6}{24}\)=0,15 mol
m CH3COOH=24g =>n CH3COOH=\(\dfrac{24}{60}\)=0,6 mol
->CH3COOH dư
=>C% (CH3COO)2Mg=\(\dfrac{0,15.142}{200+3,6-0,15.2}\).100=10,48%
=>C% CH3COOH dư= \(\dfrac{0,3.60}{200+3,6-0,15.2}\).100=8,85%
Bài 6:
\(n_{Fe\left(OH\right)_3}=\dfrac{21,4}{107}=0,2\left(mol\right)\)
PT: \(Fe\left(OH\right)_3+3HCl\rightarrow FeCl_3+3H_2O\)
_______0,2________0,6______0,2 (mol)
a, \(C\%_{HCl}=\dfrac{0,6.36,5}{200}.100\%=10,95\%\)
b, \(C\%_{FeCl_3}=\dfrac{0,2.162,5}{21,4+200}.100\%\approx14,68\%\)
Bài 7:
\(m_{H_2SO_4}=100.9,8\%=9,8\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{9,8}{98}=0,1\left(mol\right)\)
PT: \(ZnO+H_2SO_4\rightarrow ZnSO_4+H_2O\)
______0,1______0,1_______0,1 (mol)
a, \(m_{ZnO}=0,1.81=8,1\left(g\right)\)
b, \(C\%_{ZnSO_4}=\dfrac{0,1.161}{8,1+100}.100\%\approx14,89\%\)
