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Gọi: \(\left\{{}\begin{matrix}n_{FeCl_3}=x\left(mol\right)\\n_{MgCl_2}=y\left(mol\right)\end{matrix}\right.\)
PT: \(FeCl_3+3KOH\rightarrow Fe\left(OH\right)_{3\downarrow}+3KCl\)
______x_________3x_________x (mol)
\(MgCl_2+2KOH\rightarrow Mg\left(OH\right)_{2\downarrow}+2KCl\)
____y_________2y_________y (mol)
Ta có: \(n_{KOH}=0,2.2,5=0,5\left(mol\right)\)
⇒ 3x + 2y = 0,5 (1)
m kết tủa = 16,5 ⇒ 107x + 58y = 16,5 (2)
Từ (1) và (2) ⇒ x = y = 0,1 (mol)
\(\Rightarrow C_{M_{FeCl_3}}=C_{M_{MgCl_2}}=\dfrac{0,1}{0,5}=0,2\left(M\right)\)
\(FeCl_3+3KOH\rightarrow Fe\left(OH\right)_3\downarrow+3KCl\\ MgCl_2+2KOH\rightarrow Mg\left(OH\right)_2\downarrow+2KCl\)
\(n_{KOH}=0,2\cdot2,5=0,5\left(mol\right)\)
Đặt nFeCl₃ trong 500ml X là a mol, nMgCl₂ trong 500ml X là b mol
\(\Rightarrow\left\{{}\begin{matrix}3a+2b=0,5\\107a+58b=16,5\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\)
\(\Rightarrow C_MFeCl_3=\dfrac{0,1}{0,5}=0,2\left(M\right)\\ C_MMgCl_2=\dfrac{0,1}{0,5}=0,2\left(M\right)\)
\(a.n_{CuO}=\dfrac{8}{80}=0,1\left(mol\right)\\ CuO+2HCl\rightarrow CuCl_2+H_2O\\ n_{CuCl_2}=n_{CuO}=0,1\left(mol\right)\\ n_{HCl}=2.0,1=0,2\left(mol\right)\\ m_{CuCl_2}=135.0,1=13,5\left(g\right)\\ b.m_{HCl}=0,2.36,5=7,3\left(g\right)\\ c.C_{MddHCl}=\dfrac{0,2}{0,2}=1\left(M\right)\)
Em chưa biết làm dạng này như nào em? Vì dạng này rất cơ bản em ạ!
\(n_{Fe}=\dfrac{11,2}{56}=0,2mol\)
\(Fe+CuSO_4\rightarrow FeSO_4+Cu\)
0,2 0,2 0,2 ( mol )
\(m_{Cu}=0,2.64=12,8g\)
\(C_{M_{CuSO_4}}=\dfrac{0,2}{0,25}=0,8M\)
\(n_{CuSO_4}=\dfrac{15,2}{160}=0,095mol\\ CuSO_4+2NaOH\rightarrow Cu\left(OH\right)_2+Na_2SO_4\)
0,095 0,19 0,095 0,095
\(m_{rắn}=m_{Cu\left(OH\right)_2}=0,095.98=9,31g\\ V_{ddNaOH}=\dfrac{0,19}{2}=0,095l\\ b)C_{M_{Na_2SO_4}}=\dfrac{0,095}{0,04+0,095}\approx0,7M\\ c)Cu\left(OH\right)_2\xrightarrow[t^0]{}CuO+H_2O\)
0,095 0,095
\(m_{rắn}=m_{CuO}=0,095.80=7,6g\)
Bài1:
a,Vì dd A là dd bazo nên làm cho quỳ tím đổi thành màu xanh
b,\(n_{Na_2O}=\dfrac{21,7}{62}=0,35\left(mol\right)\)
PTHH: Na2O + H2O → 2NaOH
Mol: 0,35 0,7
\(\Rightarrow C_{M_{ddNaOH}}=\dfrac{0,7}{0,4}=1,75M\)
Bài 2:
a,\(n_{H_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\)
PTHH: Zn + 2HCl → ZnCl2 + H2
Mol: 0,15 0,3 0,15
⇒ a=mZn = 0,15.65 = 9,75 (g)
b,\(V_{HCl}=\dfrac{0,3}{1,5}=0,2\left(l\right)=200\left(ml\right)\)
Dung dịch A thể tích bao nhiêu? Nếu không có thì không cho đáp số.
1. \(CaCl_2+2AgNO_3\rightarrow Ca\left(NO_3\right)_2+2AgCl_{\downarrow}\)
\(n_{AgCl}=\dfrac{28,7}{143,5}=0,2\left(mol\right)\)
Theo PT: \(n_{Ca\left(NO_3\right)_2}=\dfrac{1}{2}n_{AgCl}=0,1\left(mol\right)\)
\(\Rightarrow C_{M_{Ca\left(NO_3\right)_2}}=\dfrac{0,1}{0,15+0,05}=0,5\left(M\right)\)
2. \(n_{Na}=\dfrac{2,3}{23}=0,1\left(mol\right)\)
BTNT Na, có: nNaOH = nNa = 0,1 (mol)
\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
\(2Al+2NaOH+2H_2O\rightarrow2NaAlO_2+3H_2\)
Xét tỉ lệ \(\dfrac{0,2}{2}>\dfrac{0,1}{2}\), ta được Al dư.
Theo PT: \(n_{H_2}=\dfrac{3}{2}n_{NaOH}=0,15\left(mol\right)\Rightarrow V_{H_2}=0,15.22,4=3,36\left(l\right)\)
\(n_{Al\left(pư\right)}=n_{NaOH}=0,1\left(mol\right)\Rightarrow n_{Al\left(dư\right)}=0,2-0,1=0,1\left(mol\right)\)
\(\Rightarrow m_{Al\left(dư\right)}=0,1.27=2,7\left(g\right)\)
1) \(n_{Al\left(OH\right)_3}=\dfrac{0,78}{78}=0,01\left(mol\right)\)
PTHH: \(Al_2\left(SO_4\right)_3+6NaOH\rightarrow3Na_2SO_4+2Al\left(OH\right)_3\)
0,03<----------------------0,01
=> nNaOH min = 0,03 (mol)
=> \(C_{M\left(NaOH\right)}=\dfrac{0,03}{0,2}=0,15M\)
2) \(n_{Al_2O_3}=\dfrac{5,1}{102}=0,05\left(mol\right)\)
\(n_{Al_2\left(SO_4\right)_3}=0,3.0,25=0,075\left(mol\right)\)
PTHH: \(6NaOH+Al_2\left(SO_4\right)_3\rightarrow3Na_2SO_4+2Al\left(OH\right)_3\)
0,45<------0,075-------------------------->0,15
\(NaOH+Al\left(OH\right)_3\rightarrow NaAlO_2+2H_2O\)
0,05<----0,05
\(2Al\left(OH\right)_3\underrightarrow{t^o}Al_2O_3+3H_2O\)
0,1<-------0,05
=> nNaOH max = 0,5 (mol)
=> \(V_{dd}=\dfrac{0,5}{2}=0,25\left(l\right)=250\left(ml\right)\)
3)
\(n_{KOH\left(1\right)}=0,15.1,2=0,18\left(mol\right)\)
\(n_{Al\left(OH\right)_3\left(1\right)}=\dfrac{4,68}{78}=0,06\left(mol\right)\)
\(n_{AlCl_3}=0,1.x\left(mol\right)\)
Do khi cho KOH tác dụng với dd Y xuất hiện kết tủa
=> Trong Y chứa AlCl3 dư
PTHH: \(3KOH+AlCl_3\rightarrow3KCl+Al\left(OH\right)_3\)
0,18---->0,06----------------->0,06
\(n_{KOH\left(2\right)}=0,175.1,2=0,21\left(mol\right)\)
\(n_{Al\left(OH\right)_3\left(2\right)}=\dfrac{2,34}{78}=0,03\left(mol\right)\)
PTHH: \(3KOH+AlCl_3\rightarrow3KCl+Al\left(OH\right)_3\)
(0,3x-0,18)<--(0,1x-0,06)------->(0,1x-0,06)
\(KOH+Al\left(OH\right)_3\rightarrow KAlO_2+2H_2O\)
(0,1x-0,09)<-(0,1x-0,09)
=> \(\left(0,3x-0,18\right)+\left(0,1x-0,09\right)=0,21\)
=> x = 1,2
a) PTHH: \(Na_2O+H_2O\rightarrow2NaOH\)
Ta có: \(n_{NaOH}=2n_{Na_2O}=2\cdot\dfrac{6,2}{62}=0,2\left(mol\right)\) \(\Rightarrow C_{M_{NaOH}}=\dfrac{0,2}{0,4}=0,5\left(M\right)\)
b) PTHH: \(2NaOH+CuSO_4\rightarrow Cu\left(OH\right)_2\downarrow+Na_2SO_4\)
Ta có: \(\left\{{}\begin{matrix}n_{NaOH}=0,2\left(mol\right)\\n_{CuSO_4}=0,2\cdot2,5=0,5\left(mol\right)\end{matrix}\right.\)
Xét tỉ lệ: \(\dfrac{0,2}{2}< \dfrac{0,5}{1}\) \(\Rightarrow\) CuSO4 còn dư
\(\Rightarrow\left\{{}\begin{matrix}n_{Cu\left(OH\right)_2}=0,1\left(mol\right)=n_{Na_2SO_4}\\n_{CuSO_4\left(dư\right)}=0,4\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{Cu\left(OH\right)_2}=0,1\cdot98=9,8\left(g\right)\\C_{M_{Na_2SO_4}}=\dfrac{0,1}{0,4+0,2}\approx0,17\left(M\right)\\C_{M_{CuSO_4\left(dư\right)}}=\dfrac{0,4}{0,6}\approx0,67\left(M\right)\end{matrix}\right.\)