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a. PTHH:
\(Ca+2H_2O--->Ca\left(OH\right)_2+H_2\left(1\right)\)
\(CaO+H_2O--->Ca\left(OH\right)_2\left(2\right)\)
b. Ta có: \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
Theo PT(1): \(n_{Ca}=n_{H_2}=0,1\left(mol\right)\)
\(\Rightarrow m_{Ca}=0,1.40=4\left(g\right)\)
\(\Rightarrow\%_{m_{Ca}}=\dfrac{4}{9,6}.100\%=41,7\%\)
\(\%_{m_{CaO}}=100\%-41,7\%=58,3\%\)
c. Ta có: \(n_{CaO}=\dfrac{9,6-4}{56}=0,1\left(mol\right)\)
Ta có: \(n_{hh}=0,1+0,1=0,2\left(mol\right)\)
Theo PT(1,2): \(n_{Ca\left(OH\right)_2}=n_{hh}=0,2\left(mol\right)\)
\(\Rightarrow m_{Ca\left(OH\right)_2}=0,2.74=14,8\left(g\right)\)
\(2Na+2H_2O\rightarrow2NaOH+H_2\\ Na_2O+H_2O\rightarrow2NaOH\\ n_{H_2}=\dfrac{6,72}{22,4}=0,3\left(mol\right)\\ n_{Na}=2.0,3=0,6\left(mol\right)\\ a,m_{Na}=0,6.23=13,8\left(g\right)\\ m_{Na_2O}=26,2-13,8=12,4\left(g\right)\\b, n_{Na_2O}=\dfrac{12,4}{62}=0,2\left(mol\right)\\ n_{NaOH\left(tổng\right)}=n_{Na}+2.n_{Na_2O}=0,6+\dfrac{12,4}{62}=0,8\left(mol\right)\\ m_{c.tan}=m_{NaOH}=0,8.40=32\left(g\right)\\ c,m_{ddNaOH}=m_{hh}+m_{H_2O}-m_{H_2}=26,2+200-0,3.2=225,6\left(g\right)\\ C\%_{ddNaOH}=\dfrac{32}{225,6}.100\approx14,185\%\)
Bài 14:
a) \(n_{H_2}=\dfrac{12,395}{24,79}=0,5\left(mol\right)\)
PTHH: Ca + 2H2O --> Ca(OH)2 + H2
0,5<--------------0,5<----0,5
=> mCa = 0,5.40 = 20 (g)
=> \(\left\{{}\begin{matrix}\%m_{Ca}=\dfrac{20}{34}.100\%=58,82\%\\\%m_{CaO}=100\%-58,82\%=41,18\%\end{matrix}\right.\)
b) b phải là khối lượng bazo thu được chứ nhỉ..., sao tính đc m dung dịch
\(n_{CaO}=\dfrac{34-20}{56}=0,25\left(mol\right)\)
PTHH: CaO + H2O --> Ca(OH)2
0,25---------->0,25
=> mCa(OH)2 = (0,5 + 0,25).74 = 55,5 (g)
\(n_{H_2}=\dfrac{12,395}{24,79}=0,5\left(mol\right)\)
\(Ca+2H_2O\rightarrow Ca\left(OH\right)_2+H_2\)
0,5 0,5 0,5 ( mol )
( \(CaO+H_2O\) không giải phóng \(H_2\) )
\(m_{Ca}=0,5.40=20g\)
\(\rightarrow\left\{{}\begin{matrix}\%m_{Ca}=\dfrac{20}{34}.100=58,82\%\\\%m_{CaO}=100\%-58,82\%=41,18\%\end{matrix}\right.\)
\(n_{CaO}=\dfrac{34-20}{56}=0,25\left(mol\right)\)
\(CaO+H_2O\rightarrow Ca\left(OH\right)_2\)
0,25 0,25 ( mol )
\(m_{Ca\left(OH\right)_2}=\left(0,5+0,25\right).74=55,5g\)
\(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
PTHH:
Ca + 2H2O ---> Ca(OH)2 + H2
0,1<-------------0,1<---------0,1
=> \(\left\{{}\begin{matrix}m_{Ca}=0,1.40=4\left(g\right)\\m_{CaO}=9,6-4=5,6\left(g\right)\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}\%m_{Ca}=\dfrac{4}{9,6}.100\%=41,67\%\\\%m_{CaO}=100\%-41,67\%=58,33\%\end{matrix}\right.\)
\(n_{CaO}=\dfrac{5,6}{56}=0,1\left(mol\right)\)
PTHH: CaO + H2O ---> Ca(OH)2
0,1------------------>0,1
=> \(m_{Ca\left(OH\right)_2}=\left(0,1+0,1\right).74=14,8\left(g\right)\)
Bài 1:\(PTHH:\)
\(Ca+2H_2O--->Ca(OH)_2+H_2\) \((1)\)
\(CaO+H_2O--->Ca(OH)_2 \) \((2)\)
\(a)\)
\(nH_2=\dfrac{1,68}{22,4}=0,075(mol)\)
Theo PTHH (1) \(nCa=nH_2=0,075(mol)\)
\(=> mCa=0,075.40=3(g)\)
\(=> mCaO=8,6-3=5,6(g)\)
\(b)\)
\(\%mCa=\dfrac{3.100}{8,6}=34,88\%\)
\(=>\%mCaO=100\%-34,88\%=65,12\%\)
\(c)\)
Theo PTHH (1) \(nCa(OH)2=nH_2=0,075(mol)\)\((I)\)
Ta có: \(nCaO=\dfrac{5,6}{56}=0,1(mol)\)
Theo PTHH (2) \(nCa(OH)_2=nCaO=0,1(mol)\) \((II)\)
Từ (I) và (II) => \(nCa(OH)_2 =0,075+0,1=0,175 (mol)\)
\(=> mCa(OH)_2 = 0,175.74=12,95(g)\)
Mau giúp mình lẹ những câu này chuẩn bị kt 1 tiết r @@