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a) Gọi số mol Al, Mg là a, b
=> 27a + 24b = 6,3
PTHH: 2Al + 6HCl --> 2AlCl3 + 3H2
a------------------------->1,5a
Mg + 2HCl --> MgCl2 + H2
b--------------------------->b
=> \(1,5a+b=\dfrac{6,72}{22,4}=0,3\left(mol\right)\)
=> a = 0,1; b = 0,15
=> \(\left\{{}\begin{matrix}m_{Al}=0,1.27=2,7\left(g\right)\\m_{Mg}=0,15.24=3,6\left(g\right)\end{matrix}\right.\)
b)
PTHH: MxOy + yH2 --to--> xM + yH2O
\(\dfrac{0,3}{y}\)<--0,3
=> \(M_{M_xO_y}=x.M_M+16y=\dfrac{17,4}{\dfrac{0,3}{y}}\)
=> \(M_M=21.\dfrac{2y}{x}\left(g/mol\right)\)
Xét \(\dfrac{2y}{x}=1\) => Loại
Xét \(\dfrac{2y}{x}=2\) => Loại
Xét \(\dfrac{2y}{x}=3\) => Loại
Xét \(\dfrac{2y}{x}=\dfrac{8}{3}\) => MM = 56 (g/mol) => M là Fe
a, ptpứ:
\(Mg+2HCl\rightarrow MgCl_2+H_2\left(1\right)\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\left(2\right)\)
gọi số mol Mg là x mol , số mol Al là y mol ( x; y >0)
ta có pt : \(24x+27y=6,3\left(3\right)\)
theo bài : \(nH_2=0,3mol\)
theo ptpư(1) \(nH_2=nMg=xmol\)
theo ptpư(2) \(nH_2=\dfrac{3}{2}nAl=\dfrac{3}{2}ymol\)
tiếp tục có pt : \(x+\dfrac{3}{2}y=0,3\left(4\right)\)
từ (3) và (4) ta có hệ pt:
\(24x+27y=6,3\\ x+\dfrac{3}{2}y=0,3\)
<=> \(x=0,15\) ; \(y=0,1\)
\(mMg=24x=24.0,15=3,6gam\)
\(mAl=27y=27.0,1=2,7gam\)
Bài 1:
\(n_{H_2SO_4}=\dfrac{300.19,6\%}{98}=0,6\left(mol\right);n_{Al}=\dfrac{2,7}{27}=0,1\left(mol\right)\\ PTHH:2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\\ Vì:\dfrac{0,1}{2}< \dfrac{0,6}{3}\Rightarrow H_2SO_4dư\\ n_{Al_2\left(SO_4\right)_3}=\dfrac{3n_{Al}}{2}=\dfrac{3.0,1}{2}=0,15\left(mol\right)\\ a,m_{Al_2\left(SO_4\right)_3}=342.0,15=51,3\left(g\right)\\ b,m_{ddsau}=m_{Al}+m_{ddH_2SO_4}-m_{H_2}=2,7+300-\dfrac{3}{2}.0,1.2=302,4\left(g\right)\\ c,C\%_{ddAl_2\left(SO_4\right)_3}=\dfrac{51,3}{302,4}.100\%\approx16,964\%\\ n_{H_2SO_4\left(dư\right)}=0,6-\dfrac{3}{2}.0,1=0,45\left(mol\right)\\ C\%_{ddH_2SO_4\left(dư\right)}=\dfrac{0,45.98}{302,4}.100\%\approx14,583\%\)
Bài 2:
\(PTHH:2Al+6HCl\rightarrow2AlCl_3+3H_2\\ Mg+2HCl\rightarrow MgCl_2+H_2\\ Đặt:n_{Al}=a\left(mol\right);n_{Mg}=b\left(mol\right)\left(a,b>0\right)\\ Hpt:\left\{{}\begin{matrix}27a+24b=7,8\\1,5a+b=\dfrac{8,96}{22,4}=0,4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,2\\b=0,1\end{matrix}\right.\\ \%m_{Al}=\dfrac{0,2.27}{7,8}.100\%\approx69,231\%\Rightarrow\%m_{Mg}\approx100\%-69,231\%\approx30,769\%\)
- Kim loại Cu sẽ không tan trong dung dịch HCl ở đk thường. Nên nó sẽ là kim loại duy nhất trong hỗn hợp này tác dụng với dd H2SO4 đặc,nóng .
\(Cu+2H_2SO_{4\left(đặc,nóng\right)}\rightarrow CuSO_4+SO_2+H_2O\)
Ta có: \(n_{Cu}=n_{SO_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
=> mCu= 0,1.64=6,4(g)
\(\rightarrow m_{hh\left(Mg,Al\right)}=11,5-6,4=5,1\left(g\right)\\ Đặt\left\{{}\begin{matrix}n_{Mg}=a\left(mol\right)\\n_{Al}=b\left(mol\right)\end{matrix}\right.\\ Mg+2HCl\rightarrow MgCl_2+H_2\\ 2Al+6HCl\rightarrow2AlCl_3+3H_2\\ \rightarrow\left\{{}\begin{matrix}24a+27b=5,1\\a+1,5b=\dfrac{5,6}{22,4}=0,25\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\\ \left\{{}\begin{matrix}\%m_{Cu}=\dfrac{6,4}{11,5}.100\approx55,652\%\\\%m_{Mg}=\dfrac{24.0,1}{11,5}.100\approx20,87\%\\\%m_{Al}=\dfrac{27.0,1}{11,5}.100\approx23,478\%\end{matrix}\right.\)
a)
\(n_{H_2\left(1\right)}=\dfrac{6,72}{22,4}=0,3\left(mol\right)\)
PTHH: 2Na + 2H2O --> 2NaOH + H2 (1)
0,6<----------------------0,3
=> mNa = 0,6.23 = 13,8 (g)
PTHH: Fe + 2HCl --> FeCl2 + H2
0,1<-0,2
=> mFe = 0,1.56 = 5,6 (g)
mCu = 10 (g)
\(\left\{{}\begin{matrix}\%Na=\dfrac{13,8}{13,8+5,6+10}.100\%=46,94\%\\\%Fe=\dfrac{5,6}{13,8+5,6+10}.100\%=19,05\%\\\%Cu=\dfrac{10}{13,8+5,6+10}.100\%=34,01\%\end{matrix}\right.\)
b)
PTHH: FexOy + yH2 --to--> xFe + yH2O
\(\dfrac{0,3}{y}\)<--0,3
=> \(M_{Fe_xO_y}=\dfrac{17,4}{\dfrac{0,3}{y}}=58y\left(g/mol\right)\)
=> 56x = 42y
=> \(\dfrac{x}{y}=\dfrac{3}{4}\) => CTHH: Fe3O4
a)
\(n_{H_2}=\dfrac{6,72}{22,4}=0,3\left(mol\right)\)
PTHH: 2Na + 2H2O --> 2NaOH + H2
0,6<----------------------0,3
Fe + 2HCl --> FeCl2 + H2
0,1<--0,2
=> \(\left\{{}\begin{matrix}m_{Na}=0,6.23=13,8\left(g\right)\\m_{Fe}=0,1.56=5,6\left(g\right)\\m_{Cu}=10\left(g\right)\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}\%m_{Na}=\dfrac{13,8}{13,8+5,6+10}.100\%=46,94\%\\\%m_{Fe}=\dfrac{5,6}{13,8+5,6+10}.100\%=19,05\%\\\%m_{Cu}=\dfrac{10}{13,8+5,6+10}.100\%=34,01\%\end{matrix}\right.\)
b)
PTHH: FexOy + yH2 --to--> xFe + yH2O
\(\dfrac{0,3}{y}\)<--0,3
=> \(M_{Fe_xO_y}=56x+16y=\dfrac{17,4}{\dfrac{0,3}{y}}\left(g/mol\right)\)
=> \(\dfrac{x}{y}=\dfrac{3}{4}\)
=> CTHH: Fe3O4
a) n H2 = 15,68/22,4 = 0,7(mol)
$Zn + 2HCl \to ZnCl_2 + H_2$
$Fe + 2HCl \to FeCl_2 + H_2$
Theo PTHH : nHCl = 2n H2 = 1,4(mol)
=> CM HCl = 1,4/2 = 0,7M
b) n Zn = a(mol) ; n Fe = b(mol) => 65a + 56b = 43,7(1)
n H2 = a + b = 0,7(2)
Từ (1)(2) suy ra a = 0,5 ; b = 0,2
Suy ra:
m Zn = 0,5.65 = 32,5 gam
m Fe = 0,2.56 = 11,2 gam
a) n H2 = 15,68/22,4 = 0,7(mol)
Zn+2HCl→ZnCl2+H2Zn+2HCl→ZnCl2+H2
Fe+2HCl→FeCl2+H2Fe+2HCl→FeCl2+H2
Theo PTHH : nHCl = 2n H2 = 1,4(mol)
=> CM HCl = 1,4/2 = 0,7M
b) n Zn = a(mol) ; n Fe = b(mol) => 65a + 56b = 43,7(1)
n H2 = a + b = 0,7(2)
Từ (1)(2) suy ra a = 0,5 ; b = 0,2
Suy ra:
m Zn = 0,5.65 = 32,5 gam
m Fe = 0,2.56 = 11,2 gam
PTHH: Fe + 2HCl -> FeCl2 + H2
Mol: 0,2 <--- 0,4
Đặt nFe2O3 = a (mol); nFeO = b (mol)
160a + 72b = 15,2 (1)
PTHH: Fe2O3 + 3H2 -> (to) 2Fe + 3H2O
Mol: a ---> 3a ---> 2a
FeO + H2 -> (to) Fe + H2O
Mol: b ---> b ---> b
2a + b = 0,2 (2)
(1)(2) => a = 0,05 (mol); b = 0,1 (mol)
mFe2O3 = 0,05 . 160 = 8 (g)
%mFe2O3 = 8/15,2 = 52,63%
%mFeO = 100% - 52,63% = 47,37%
nH2 = 0,05 . 3 + 0,1 = 0,25 (mol)
VH2 = 0,25 . 22,4 = 5,6 (l)
