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\(n_{KOH}=\dfrac{22,4}{56}=0,4(mol)\\ a,PTHH:MgCl_2+2KOH\to Mg(OH)_2\downarrow+2KCl\\ Mg(OH)_2\buildrel{{t^o}}\over\to MgO+H_2O\\ b,\text {Vì } \dfrac{n_{MgCl_2}}{1}<\dfrac{n_{KOH}}{2} \Rightarrow \text {KOH dư}\\ \Rightarrow n_{MgO}=n_{Mg(OH)_2}=n_{MgCl_2}=0,15(mol)\\ \Rightarrow m_{MgO}=0,15.40=6(g)\\ c,\text {Chất tan trong nước lọc là KCl}\\ \text {Theo PT: }n_{KCl}=2n_{MgCl_2}=0,3(mol)\\ \Rightarrow m_{KCl}=0,3.74,5=22,35(g)\)
a, \(CuCl_2+2KOH\rightarrow Cu\left(OH\right)_2+2KCl\)
\(Cu\left(OH\right)_2\underrightarrow{t^o}CuO+H_2O\)
b, \(n_{CuCl_2}=\dfrac{20,25}{135}=0,15\left(mol\right)\)
Theo PT: \(n_{KOH}=2n_{CuCl_2}=0,3\left(mol\right)\)
\(\Rightarrow C_{M_{KOH}}=\dfrac{0,3}{0,3}=1\left(M\right)\)
c, \(n_{CuO}=n_{Cu\left(OH\right)_2}=n_{CuCl_2}=0,15\left(mol\right)\)
\(\Rightarrow m_{CuO}=0,15.80=12\left(g\right)\)
\(a,PTHH:CuCl_2+2NaOH\rightarrow Cu\left(OH\right)_2+2NaCl\\ Cu\left(OH\right)_2\rightarrow^{t^0}CuO+H_2O\\ b,n_{CuCl_2}=n_{Cu\left(OH\right)_2}=n_{CuO}=0,2\left(mol\right)\\ \Rightarrow m_{CuO}=0,2\cdot80=16\left(g\right)\\ c,n_{NaCl}=2n_{CuCl_2}=0,4\left(mol\right)\\ \Rightarrow m_{NaCl}=0,4\cdot58,5=23,4\left(g\right)\\ \Rightarrow C\%_{NaCl}=\dfrac{23,4}{200}\cdot100\%=11,7\%\)
a, \(FeCl_3+3NaOH\rightarrow3NaCl+Fe\left(OH\right)_3\)
\(2Fe\left(OH\right)_3\underrightarrow{t^o}Fe_2O_3+3H_2O\)
b, \(n_{FeCl_3}=0,4.2=0,8\left(mol\right)\)
Theo PT: \(n_{NaCl}=3n_{FeCl_3}=2,4\left(mol\right)\)
\(\Rightarrow C_{M_{NaCl}}=\dfrac{2,4}{0,4+0,2}=4\left(M\right)\)
c, \(n_{Fe_2O_3}=\dfrac{1}{2}n_{Fe\left(OH\right)_3}=\dfrac{1}{2}n_{FeCl_3}=0,4\left(mol\right)\)
\(\Rightarrow m_{Fe_2O_3}=0,4.160=64\left(g\right)\)
\(n_{FeCl3}=2.0,4=0,8\left(mol\right)\)
PTHH : \(FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3+3NaCl\)
0,8----------------------->0,8----------->2,4
b) \(C_{MNaCl}=\dfrac{2,4}{0,4+0,2}=4M\)
c) \(2Fe\left(OH\right)_3\xrightarrow[]{t^o}Fe_2O_3+3H_2O\)
0,8--------------->0,4
\(\Rightarrow a=m_{Fe2O3}=0,4.160=64\left(g\right)\)
a) MgCl2+ 2NaOH→ 2NaCl+ Mg(OH)2↓
(mol) 0,15 0,3 0,3 0,15
Mg(OH)2→ MgO+ H2O
(mol) 0,15 0,15
b)
\(n_{NaOH}=\dfrac{m}{M}=\dfrac{18}{40}=0,45\left(mol\right)\)
Xét tỉ lệ:
MgCl2 NaOH
0,15 < \(\dfrac{0,45}{2}\)
-> MgCl2 phản ứng hết, NaOH dư
-> \(m_{MgO}=n.M=0,15.40=6\left(g\right)\)
c)
\(m_{NaOH\left(dư\right)}=m_{NaOH\left(bđ\right)}-m_{NaOH\left(ph.ứng\right)}\)= 0,45.40-0,3.40= 6(g)
mNaCl=n.M=0,3.58,5= 17,55(g)