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Gọi nFe=a(mol);nM=b(mol)⇒56a+Mb=9,6(1)
Fe+2HCl→FeCl2+H2
M+2HCl→MCl2+H2
nH2=a+b=0,2⇒a=0,2−b
Ta có :
56a+Mb=9,656a+Mb=9,6
⇔56(0,2−b)+Mb=9,6
⇔Mb−56b=−1,6
⇔b(56−M)=1,6
⇔b=1,656−M
Mà 0<b<0,20<b<0,2
Suy ra : 0<1,656−M<0,20<1,656−M<0,2
⇔M<48(1)
M+2HCl→MCl2+H2
nM=nH2<5,622,4=0,25
⇒MM>4,60,25=18,4
+) Nếu M=24(Mg)
Ta có :
56a+24b=9,656a+24b=9,6
a+b=0,2a+b=0,2
Suy ra a = 0,15 ; b = 0,05
mFe=0,15.56=8,4(gam)
mMg=0,05.24=1,2(gam)
+) Nếu M=40(Ca)
56a+40b=9,656a+40b=9,6
a+b=0,2
Suy ra a = b = 0,1
mCa=0,1.40=4(gam)
mFe=0,1.56=5,6(gam)
\(n_{O_2}=\dfrac{5.6}{22.4}=0.25\left(mol\right)\)
\(n_{H_2}=\dfrac{10.08}{22.4}=0.45\left(mol\right)\)
\(n_{Fe}=a\left(mol\right),n_{Al}=b\left(mol\right)\)
\(3Fe+2O_2\underrightarrow{^{^{t^0}}}Fe_3O_4\)
\(a.......\dfrac{2a}{3}\)
\(4Al+3O_2\underrightarrow{^{^{t^0}}}2Al_2O_3\)
\(b.......\dfrac{3b}{4}\)
\(n_{O_2}=\dfrac{2a}{3}+\dfrac{3b}{4}=0.25\left(mol\right)\left(1\right)\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
\(n_{H_2}=a+1.5b=0.45\left(mol\right)\left(2\right)\)
\(\left(1\right),\left(2\right):a=0.15,b=0.2\)
\(m_{Fe}=0.15\cdot56=8.4\left(g\right)\)
\(m_{Al}=0.2\cdot27=5.4\left(g\right)\)
\(\%m_{Fe}=\dfrac{8.4}{8.4+5.4}\cdot100\%=60.8\%\)
\(\%m_{Al}=100-60.8=39.2\%\)
a) CuO + H2 -> Cu + H2O (1)
ZnO + H2 -> Zn + H2O (2)
n\(_{H_2}\) = \(\dfrac{4,48}{22,4}\) = 0,2 (mol) => m\(H_2\) = 0,2.2 = 0,4 (g)
Theo PT (1) và (2) ta có: n\(H_2O\) = n\(H_2\) = 0,2 (mol)
=> m\(H_2O\) = 0,2.18 = 3,6 (g)
Theo định luật bảo toàn khối lượng ta có:
mhh + m\(H_2\) = mkim loại + m\(H_2O\)
=> mhh = 12,9 + 3,6 - 0,4 = 16,1 (g)
b) Gọi mCu là x(g) (0<x<12,9) => nCu = \(\dfrac{x}{64}\) (mol)
Thì mZn là 12,9-x (g) => nZn = \(\dfrac{12,9-x}{65}\) (mol)
Theo PT (1) ta có: n\(H_2\) = nCu = \(\dfrac{x}{64}\) (mol)
Theo PT (2) ta có: n\(H_2\) = nZn = \(\dfrac{12,9-x}{65}\) (mol)
Theo đề bài, n\(H_2\) là 0,2mol nên ta có:
\(\dfrac{x}{64}+\dfrac{12,9-x}{65}=0,2\) <=> x = 6,4 (g)
=> mCu = 6,4 (g)
Vậy: %Cu = \(\dfrac{6,4}{12,9}\).100% \(\approx\) 49,61%
%Zn = 100% - 49,61% = 50,39%
\(a.n_{H_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\\ 2Al+6HCl\rightarrow2AlCl_3+3H_2\\ a............3a.......a.........1,5a\left(mol\right)\\ Fe+2HCl\rightarrow FeCl_2+H_2\\ b.........2b........b.........b\left(mol\right)\\ \rightarrow\left\{{}\begin{matrix}27a+56b=5,5\\1,5a+b=0,2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,05\end{matrix}\right.\\ \rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{27.0,1}{5,5}.100\approx49,091\%\\\%m_{Fe}=\dfrac{0,05.56}{5,5}.100\approx50,909\%\end{matrix}\right.\\ b.C_{MddHCl}=\dfrac{3a+2b}{0,5}=\dfrac{3.0,1+2.0,05}{0,5}=0,8\left(M\right)\)
ta co pthh
Fe3O4+4 H2 \(\rightarrow\)3Fe +4 H2O
ZnO+H2 \(\rightarrow\)Zn + H2O
Theo de bai ta co nH2= \(\dfrac{6,72}{22,4}=0,3mol\)
goi x la so mol cua H2 tham gia vao pthh 1
so mol cua H2 tham gia vao pthh 2 la 0,3-x mol
theo pthh 1 nFe3O4= \(\dfrac{1}{4}nH2=\dfrac{1}{4}x\) mol
theo pthh 2 nZnO=nH2= 0,3-x mol
theo de bai ta co
232.\(\dfrac{1}{4}x\)+ 81.(0,3-x)=19,7
\(\Leftrightarrow\)58x + 24,3 -81x = 19,7
\(\Leftrightarrow\)-23x=19,7-24,3
\(\Leftrightarrow\)-23x=-4,6
\(\Rightarrow\)x= \(\dfrac{-4,6}{-23}=0,2mol\)
\(\Rightarrow\)nFe3O4=\(\dfrac{1}{4}nH2=\dfrac{1}{4}.0,2=0,05mol\)
nZnO=nH2=0,3-0,2=0,1 mol
\(\Rightarrow\)Khoi luong moi oxit trong hh la
mFe3O4=232.0,05=11,6 g
mZnO= mhh-mFe3O4=19,7-11,6=8,1 g
Theo pthh1 nFe= \(\dfrac{3}{4}nH2=\dfrac{3}{4}.0,2=0,15mol\)
\(\Rightarrow\)mFe= 0,15.56=8,4 g
theo pthh 2 nZn=nH2= 0,1 mol
\(\Rightarrow\)mZn=0,1.65=6,5 g