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a)PTHH: ZnCl2+2KOH---->Zn(OH)2+2KCl
b)
mZnCl2=204.10100=20,4(g)ZnCl2=204.10100=20,4(g)
nZnCl2=20,4136=0,15(mol)ZnCl2=20,4136=0,15(mol)
nKOH=112.20%56=0,4(mol)KOH=112.20%56=0,4(mol)
=> 0,15/1 < 0,4/1=> KOH dư
Theo pthh, ta có :
nCu(OH)2=nZnCl2=0,15(mol)Cu(OH)2=nZnCl2=0,15(mol)
mCu(OH)2=0,15.98=14,7(g)Cu(OH)2=0,15.98=14,7(g)
c) m dd sau pư=204+112=316(g)
Theo pthh
nKOH=2nZnCl2=0,3(mol)KOH=2nZnCl2=0,3(mol)
C% KOH=0,3.56326.100%=5,32%0,3.56326.100%=5,32%
nKCl=2nZnCl2=0,3(mol)KCl=2nZnCl2=0,3(mol)
C% KCl=0,3.74,5316.100%=7,07%
\(a,PTHH:CuCl_2+2KOH\rightarrow Cu\left(OH\right)_2+2KCl\\ ...0,2......0,4.......0,2........0,4\left(mol\right)\\ b,n_{CuCl_2}=\dfrac{27}{135}=0,2\left(mol\right)\\ m_{Cu\left(OH\right)_2}=0,2\cdot98=19,6\left(g\right)\\ c,m_{KOH}=0,4\cdot56=22,4\left(g\right)\\ m_{dd_{KOH}}=\dfrac{22,4\cdot100\%}{20\%}=112\left(g\right)\\ m_{dd_{KCl}}=m_{CuCl_2}+m_{dd_{KOH}}-m_{Cu\left(OH\right)_2}=27+112-19,6=119,4\left(g\right)\)
\(d,C\%_{dd_{KCl}}=\dfrac{74,5\cdot0,4}{119,4}\cdot100\%\approx24,96\%\)
a, \(H_2SO_4+BaCl_2\rightarrow BaSO_{4\downarrow}+2HCl\)
b, Ta có: \(m_{H_2SO_4}=114.20\%=22,8\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{22,8}{96}=0,2375\left(mol\right)\)
\(m_{BaCl_2}=400.5,2\%=20,8\left(g\right)\Rightarrow n_{BaCl_2}=\dfrac{20,8}{208}=0,1\left(mol\right)\)
Xét tỉ lệ: \(\dfrac{0,2375}{1}>\dfrac{0,1}{1}\), ta được H2SO4 dư.
Theo PT: \(n_{BaSO_4}=n_{BaCl_2}=0,1\left(mol\right)\Rightarrow m_{BaSO_4}=0,1.233=23,3\left(g\right)\)
c, Theo PT: \(\left\{{}\begin{matrix}n_{H_2SO_4\left(pư\right)}=n_{BaCl_2}=0,1\left(mol\right)\\n_{HCl}=2n_{BaCl_2}=0,2\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow n_{H_2SO_4\left(dư\right)}=0,2375-0,1=0,1375\left(mol\right)\)
Ta có: m dd sau pư = 114 + 400 - 23,3 = 490,7 (g)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{H_2SO_4\left(dư\right)}=\dfrac{0,1375.98}{490,7}.100\%\approx2,75\%\\C\%_{HCl}=\dfrac{0,2.36,5}{490,7}.100\%\approx1,49\%\end{matrix}\right.\)
Câu 3 :
\(m_{ct}=\dfrac{10.80}{100}=8\left(g\right)\)
\(n_{NaOH}=\dfrac{8}{40}=0,2\left(mol\right)\)
a) Hiện tượng : Xuất hiện kết tủa trắng
Pt : \(2NaOH+MgSO_4\rightarrow Na_2SO_4+Mg\left(OH\right)_2|\)
2 1 1 1
0,2 0,1 0,1 0,1
\(n_{Mg\left(OH\right)2}=\dfrac{0,2.1}{2}=0,1\left(mol\right)\)
⇒ \(m_{Mg\left(OH\right)2}=0,1.58=5,8\left(g\right)\)
b) \(n_{MgSO4}=\dfrac{0,2.1}{2}=0,1\left(mol\right)\)
\(m_{MgSO4}=0,1.120=12\left(g\right)\)
\(m_{ddMgSO}=\dfrac{12.100}{10}=120\left(g\right)\)
c) \(n_{Na2SO4}=\dfrac{0,1.1}{1}=0,1\left(mol\right)\)
⇒ \(m_{Na2SO4}=0,1.142=14,2\left(g\right)\)
\(m_{ddspu}=80+120-5,8=194,2\left(g\right)\)
\(C_{Na2SO4}=\dfrac{14,2.100}{194,2}=7,31\)0/0
Chúc bạn học tốt
Câu 4 :
\(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)
Pt : \(Fe+H_2SO_4\rightarrow FeSO_4+H_2|\)
1 1 1 1
0,2 0,2
\(n_{H2SO4}=\dfrac{0,2.1}{1}=0,2\left(mol\right)\)
\(m_{H2SO4}=0,2.98=19,6\left(g\right)\)
\(m_{ddH2SO4}=\dfrac{19,6.100}{20}=98\left(g\right)\)
\(V_{ddH2SO4}=\dfrac{98}{1,2}\simeq81,67\left(ml\right)\)
Chúc bạn học tốt
a) \(n_{CO_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)
PTHH: 2HCl + CaCO3 → CaCl2 + CO2 + H2O
Mol: 0,4 0,2 0,2
b) \(C\%_{ddHCl}=\dfrac{0,4.36,5.100\%}{100}=14,6\%\)
c) \(m_{CaCl_2}=0,2.101=20,2\left(g\right)\)
\(m_{Fe_2\left(SO_4\right)_3}=\dfrac{200\cdot20}{100}=40\left(g\right)\Rightarrow n=0,1mol\)
\(Fe_2\left(SO_4\right)_3+6NaOH\rightarrow2Fe\left(OH\right)_3\downarrow+3Na_2SO_4\)
0,1 0,6 0,2 0,3
a)\(m_{NaOH}=0,6\cdot40=24\left(g\right)\)
b)\(m_{Fe\left(OH\right)_3}=0,2\cdot107=21,4\left(g\right)\)
c)\(m_{Na_2SO_4}=0,3\cdot142=42,6\left(g\right)\)
\(m_{ddsau}=200+24-21,4=202,6\left(g\right)\)
\(\Rightarrow C\%=\dfrac{42,6}{202,6}\cdot100\%=21,03\%\)
a)
$K_2SO_4 + BaCl_2 \to BaSO_4 + 2KCl$
b)
$n_{K_2SO_4} = 0,2.2 = 0,4(mol)$
$n_{BaCl_2} = 0,3.1 = 0,3(mol)$
Ta thấy :
$n_{K_2SO_4} : 1 > n_{BaCl_2} : 1$ nên $K_2SO_4$ dư
$n_{BaSO_4} = n_{BaCl_2} = 0,3(mol)$
$m_{BaSO_4} = 0,3.233 = 69,9(gam)$
c) $n_{K_2SO_4} = 0,4 - 0,3 = 0,1(mol)$
$V_{dd\ sau\ pư} = 0,2 + 0,3 = 0,5(lít)$
$C_{M_{K_2SO_4} } = \dfrac{0,1}{0,5} = 0,2M$
$C_{M_{KCl}} = \dfrac{0,6}{0,5} = 1,2M$
a) ZnCl2+2KOH---->Zn(OH)2+2KCl
b)
m\(_{ZnCl2}=\frac{204.10}{100}=20,4\left(g\right)\)
n\(_{ }\)\(_{ZnCl2}=\frac{20,4}{136}=0,15\left(mol\right)\)
n\(_{KOH}=\frac{112.20\%}{56}=0,4\left(mol\right)\)
=> KOH dư
Theo pthh
n\(_{Cu\left(OH\right)2}=n_{ZnCl2}=0,15\left(mol\right)\)
m\(_{Cu\left(OH\right)2}=0,15.98=14,7\left(g\right)\)
c) m dd sau pư=204+112=316(g)
Theo pthh
n\(_{KOH}=2n_{ZnCl2}=0,3\left(mol\right)\)
C% KOH=\(\frac{0,3.56}{326}.100\%=5,32\%\)
n\(_{KCl}=2n_{ZnCl2}=0,3\left(mol\right)\)
C% KCl=\(\frac{0,3.74,5}{316}.100\%=7,07\%\)