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Cho kim loại Magie tác dụng vừa đủ với 200 gam dung dịch axit axetic 15%.
a. Tính khối lượng Magie phản ứng ?
b. Tính nồng độ phần trăm dung dịch muối thu được sau phản ứng ?
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mCH3COOH= 200.15%= 30(g) => nCH3COOH= 30/60=0,5(mol)
a) Mg + 2 CH3COOH -> (CH3COO)2Mg + H2
0,25___0,5_______0,25_____________0,25(mol)
mMg= 0,25.24= 6(g)
b) m(CH3COO)2Mg=142.0,25=35,5(g)
mdd(CH3COO)2Mg= 6+200-0,25.2=205,5(g)
=> \(C\%dd\left(CH3COO\right)2Mg=\frac{35,5}{205,5}.100\approx17,275\%\)
Ta có:
\(n_{Zn}=\frac{13}{65}=0,2\left(mol\right)\)
\(2CH_3COOH+Zn\rightarrow\left(CH_3COO\right)_2Zn+H_2\)
\(\Rightarrow n_{CH3COOH}=2n_{Zn}=0,2.2=0,4\left(mol\right)\)
\(m_{dd\left(CH3COOH\right)}=\frac{0,4.60}{12\%}=200\left(g\right)\)
\(n_{H2}=n_{Zn}=0,2\left(mol\right)\Rightarrow m_{dd\left(spu\right)}=212,6\left(g\right)\)
\(n_{\left(CH3COO\right)2Zn}=n_{Zn}=0,2\left(mol\right)\)
\(\Rightarrow C\%_{\left(CH3COO\right)2Zn}=\frac{0,2.183}{212,6}.100\%=17,22\%\)
\(a,m_{Na_2CO_3}=\dfrac{500.20}{100}=100\left(g\right)\\ \rightarrow n_{Na_2CO_3}=\dfrac{100}{106}=\dfrac{50}{53}\left(mol\right)\)
PTHH: \(Na_2CO_3+2CH_3COOH\rightarrow2CH_3COONa+CO_2\uparrow+H_2O\)
\(\dfrac{50}{53}\)------->\(\dfrac{100}{53}\)--------------->\(\dfrac{100}{53}\)-------------->\(\dfrac{50}{53}\)
\(b,m_{axit}=\dfrac{100}{53}.60=\dfrac{6000}{53}\left(g\right)\\ c,m_{dd}=500+400-\dfrac{50}{53}.44=\dfrac{45500}{53}\left(g\right)\\ m_{CH_3COONa}=\dfrac{100}{53}.82=\dfrac{8200}{53}\left(g\right)\\ \rightarrow C\%_{CH_3COONa}=\dfrac{\dfrac{8200}{23}}{\dfrac{45500}{23}}.100\%=18,02\%\)
a) \(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\)
\(m_{H_2SO_4}=147.10\%=14,7\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{14,7}{98}=0,15\left(mol\right)\)
PTHH: Zn + H2SO4 → ZnSO4 + H2
Mol: 0,1 0,1 0,1 0,1
Ta có: \(\dfrac{0,1}{1}< \dfrac{0,15}{1}\) ⇒ Zn hết, H2SO4 dư
b) \(V_{H_2}=0,1.22,4=2,24\left(l\right)\)
c) mdd sau pứ = 6,5 + 147 - 0,1.2 = 153,3 (g)
\(C\%_{ddZnSO_4}=\dfrac{0,1.161.100\%}{153,3}=10,502\%\)
\(C\%_{ddH_2SO_4dư}=\dfrac{\left(0,15-0,1\right).98.100\%}{153,3}=3,196\%\)
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) \(m_{dd.sau.pư}=1,325+25-0,0125.44=25,775\left(g\right)\)
\(C\%_{dd.CH_3COONa}=\dfrac{0,025.82}{25,775}.100\%=7,95\%\)
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, $m_{dd} = 11,2 + 200 - 0,2.2 = 210,8(gam)$
$C\%_{FeCl_2} = \dfrac{0,2.127}{210,8}.100\% = 12,05\%$
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, \(C\%_{ZnSO_4}=\dfrac{0,1.161}{8,1+100}.100\%\approx14,89\%\)
\(n_{H_2}=\dfrac{1,12}{22,4}=0,05\left(mol\right)\\ a.Zn+2HCl\rightarrow ZnCl_2+H_2\\ 0,05.........0,1..........0,05..........0,05\left(mol\right)\\ a.C\%_{ddHCl}=\dfrac{0,1.36,5}{200}.100=1,825\%\\ b.m_{Zn}=0,05.65=3,25\left(g\right)\\ c.C\%_{ddZnCl_2}=\dfrac{136.0,05}{3,25+200-0,05.2}.100\approx3,347\%\)
a) \(n_{CuO}=\dfrac{4}{80}=0,05\left(mol\right)\)
PTHH: CuO + 2HCl --> CuCl2 + H2O
0,05---->0,1----->0,05--->0,05
=> \(C\%\left(HCl\right)=\dfrac{0,1.36,5}{150}.100\%=2,433\%\)
b) \(C\%\left(CuCl_2\right)=\dfrac{0,05.135}{4+150}.100\%=4,383\%\)