Cho 12 gam Magie tác dụng vừa đủ với dung dịch H2SO4 loãng.
a, Tính thể tích H2 thu được ở đktc?
b, Cho khí H2 thu được ở trên đi qua bình đựng CuO nung nóng. Tính khối lượng Cu thu được?
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\(n_{Al}=\dfrac{16,2}{27}=0,6\left(mol\right)\)
2Al + 3H2SO4 ---> Al2(SO4)3 + 3H2
0,6 0,9 0,3 0,9
\(\rightarrow V_{H_2}=0,9.22,4=20,16\left(l\right)\)
\(n_{Cu}=\dfrac{57}{64}=0,890625\left(mol\right)\)
PTHH: CuO + H2 --to--> Cu + H2O
0,890625 0,890625
\(H=\dfrac{0,890625}{0,9}=99\%\)
\(n_{Mg}=\dfrac{4.8}{24}=0.2\left(mol\right)\)
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(0.2.......0.4........................0.2\)
\(C_{M_{HCl}}=\dfrac{0.4}{0.2}=2\left(M\right)\)
\(n_{CuO}=\dfrac{32}{80}=0.4\left(mol\right)\)
\(CuO+H_2\underrightarrow{^{^{t^0}}}Cu+H_2O\)
Lập tỉ lệ : \(\dfrac{0.4}{1}>\dfrac{0.2}{1}\)
=> CuO dư
\(m_{cr}=m_{CuO\left(dư\right)}+m_{Cu}=32-0.2\cdot80+0.2\cdot64=28.8\left(g\right)\)
\(\%Cu=\dfrac{0.2\cdot64}{28.8}\cdot100\%=44.44\%\)
\(\%CuO\left(dư\right)=55.56\%\)
\(n_{Al}=\dfrac{2,7}{27}=0,1\left(mol\right)\)
PTHH: 2Al + 6HCl ---> 2AlCl3 + 3H2
0,1 0,15
=> VH2 = 0,15.22,4 = 3,36 (l)
\(n_{CuO}=\dfrac{32}{80}=0,4\left(mol\right)\)
PTHH: CuO + H2 --to--> Cu + H2O
LTL: \(0,4>0,15\rightarrow\) CuO dư
Theo pthh: \(n_{CuO\left(pư\right)}=n_{Cu}=n_{H_2}=0,15\left(mol\right)\)
\(\rightarrow\left\{{}\begin{matrix}\%m_{Cu}=\dfrac{0,15.64}{0,15.64+\left(0,4-0,15\right).80}=32,43\%\\\%m_{CuO}=100\%-32,43\%=67,57\%\end{matrix}\right.\)
a. \(2Al+6HCl\rightarrow2AlCl_3+3H_2\left(1\right)\)
b. \(n_{Al}=\frac{m}{M}=\frac{2,7}{27}=0,1mol\)
Theo phương trình `(1)` \(n_{H_2}=\frac{3}{2}.n_{Al}=\frac{3}{2}.0,1=0,15mol\)
\(\rightarrow V_{H_2\left(ĐKTC\right)}=n.22,4=0,15.22,4=3,36l\)
c. \(CuO+H_2\rightarrow^{t^o}Cu+H_2O\left(2\right)\)
\(n_{CuO}=\frac{m}{M}=\frac{32}{80}=0,4mol\)
Tỷ lệ \(\frac{0,4}{1}>\frac{0,15}{1}\)
`->CuO` dư
Theo phương trình `(2)` \(n_{Cu}=n_{H_2}=0,15mol\)
\(n_{CuO\left(pứ\right)}=n_{H_2}=0,15mol\)
\(\rightarrow n_{CuO\left(dư\right)}=0,4-0,15=0,25mol\)
\(m\left(g\right)\text{ chất rắn }\hept{\begin{cases}CuO_{dư}=0,25mol\\Cu=0,15mol\end{cases}}\)
\(\rightarrow m=0,15.64+0,25.80=29,6g\)
\(\%m_{CuO\left(dư\right)}=\frac{0,25.80.100}{29,6}\approx67,6\%\)
\(\%m_{Cu}=100\%-67,6\%=32,4\%\)
\(n_{Zn}=\dfrac{m}{M}=\dfrac{3,25}{65}=0,05\left(mol\right)\)
\(PTHH:Zn+2HCl\rightarrow ZnCl_2+H_2\)
1 2 1 1
0,05 0,1 0,05 0,05
a) \(V_{H_2}=n.24,79=0,05.24,79=1,2395\left(l\right)\)
\(m_{ZnCl_2}=n.M=0,05.\left(65+35,5.2\right)=6,8\left(g\right)\)
b) \(PTHH:CuO+H_2\underrightarrow{t^o}Cu+H_2O\)
Ta cos tỉ lệ: \(\dfrac{0,1}{1}>\dfrac{0,05}{1}\Rightarrow\) CuO dư.
Theo ptr, ta có: \(n_{Cu}=n_{H_2}=0,05mol\\ \Rightarrow m_{Cu}=n.M=0,05.64=3,2\left(g\right).\)
a, PT: \(Zn+2HCl\rightarrow ZnCl_2+H_2\)
Ta có: \(n_{Zn}=\dfrac{3,25}{65}=0,05\left(mol\right)\)
THeo PT: \(n_{ZnCl_2}=n_{H_2}=n_{Zn}=0,05\left(mol\right)\)
\(\Rightarrow V_{H_2}=0,05.24,79=1,2395\left(l\right)\)
\(m_{ZnCl_2}=0,05.136=6,8\left(g\right)\)
b, Ta có: \(n_{CuO}=\dfrac{8}{80}=0,1\left(mol\right)\)
PT: \(CuO+H_2\underrightarrow{t^o}Cu+H_2O\)
Xét tỉ lệ: \(\dfrac{0,1}{1}>\dfrac{0,05}{1}\), ta được CuO dư.
Theo PT: \(n_{Cu}=n_{H_2}=0,05\left(mol\right)\Rightarrow m_{Cu}=0,05.64=3,2\left(g\right)\)
a.b.\(n_{Al}=\dfrac{m_{Al}}{M_{Al}}=\dfrac{2,7}{27}=0,1mol\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
0,1 0,15 ( mol )
\(V_{H_2}=n_{H_2}.22,4=0,15.22,4=3,36l\)
c.\(n_{CuO}=\dfrac{m_{CuO}}{M_{CuO}}=\dfrac{16}{80}=0,2mol\)
\(CuO+H_2\rightarrow\left(t^o\right)Cu+H_2O\)
0,2 < 0,15 ( mol )
0,15 0,15 0,15 ( mol )
\(m_A=m_{CuO\left(dư\right)}+m_{Cu}=\left[\left(0,2-0,15\right).80\right]+\left[0,15.64\right]=4+9,6=13,6g\)
a.b.\(n_{Al}=\dfrac{m_{Al}}{M_{Al}}=\dfrac{5,4}{27}=0,2mol\)
\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)
0,2 0,3 ( mol )
\(V_{H_2}=n_{H_2}.22,4=0,3.22,4=6,72l\)
c.\(n_{CuO}=\dfrac{m_{CuO}}{M_{CuO}}=\dfrac{32}{80}=0,4mol\)
\(CuO+H_2\rightarrow Cu+H_2O\)
0,4 < 0,3 ( mol )
0,3 0,3 0,3 ( mol )
\(m_A=m_{CuO\left(du\right)}+m_{Cu}=\left[\left(0,4-0,3\right).80\right]+\left(0,3.64\right)=8+19,2=27,2g\)
a) \(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
PTHH: 2Al + 6HCl --> 2AlCl3 + 3H2
0,2---------------------->0,3
=> VH2 = 0,3.22,4 = 6,72 (l)
b)
\(n_{CuO}=\dfrac{32}{80}=0,4\left(mol\right)\)
PTHH: CuO + H2 --to--> Cu + H2O
Xét tỉ lệ: \(\dfrac{0,4}{1}>\dfrac{0,3}{1}\) => CuO dư, H2 hết
PTHH: CuO + H2 --to--> Cu + H2O
0,3<--0,3------->0,3
=> Rắn sau pư gồm \(\left\{{}\begin{matrix}Cu:0,3\left(mol\right)\\CuO\left(dư\right):0,1\left(mol\right)\end{matrix}\right.\)
\(\left\{{}\begin{matrix}\%m_{Cu}=\dfrac{0,3.64}{0,3.64+0,1.80}.100\%=70,59\%\\\%m_{CuO}=\dfrac{0,1.80}{0,3.64+0,1.80}.100\%=29,41\%\end{matrix}\right.\)
\(n_{Fe}=\dfrac{m}{M}=\dfrac{8,4}{56}=0,15mol\)
PTHH: Fe + 2HCl \(\rightarrow\) FeCl2 + H2
TL: 1 2 1 1
mol: 0,15 \(\rightarrow\) 0,3 \(\rightarrow\) 0,15 \(\rightarrow\) 0,15
Đổi \(100ml=0,1l\)
\(b.C_{M_{ddHCl}}=\dfrac{n}{V_{dd}}=\dfrac{0,3}{0,1}=3M\)
\(c.V_{H_2}=n.22,4=0,15.22,4=33,6l\)
d. Ta có: \(n_{H_2}=0,15mol\)
PTHH: H2 + CuO \(\rightarrow\) Cu + H2O
TL: 1 1 1 1
mol: 0,15 \(\rightarrow\) 0,15 \(\rightarrow\) 0,15 \(\rightarrow\) 0,15
\(n_{CuO}=\dfrac{m}{M}=\dfrac{20}{80}=0,25mol\)
Lập tỉ lệ: \(\dfrac{n_{H_2}}{1}:\dfrac{n_{CuO}}{1}\)
\(\Leftrightarrow=\dfrac{0,15}{1}< \dfrac{0,25}{1}\)
\(\Rightarrow\) H2 hết, CuO dư \(\Rightarrow\) Tính theo H2
\(m_{CuO}=n.M=0,15.64=9,6g\)
a. \(n_{Zn}=\dfrac{2,6}{65}=0,04\left(mol\right)\)
\(PTHH:Zn+H_2SO_4\rightarrow ZnSO_4+H_2\uparrow\)
- Mol theo PTHH : \(1:1:1:1\)
- Mol theo phản ứng : \(0,04\rightarrow0,04\rightarrow0,04\rightarrow0,04\)
\(\Rightarrow m_{ZnSO_4}=n_{ZnSO_4}.M_{ZnSO_4}=0,04.161=6,44\left(g\right)\)
b. Từ a. suy ra : \(V_{H_2}=n_{H_2}.22,4=0,04.22,4=0,896\left(l\right)\)
c. Từ a. suy ra : \(n_{H_2}=0,04\left(mol\right)\)
\(PTHH:H_2+PbO\underrightarrow{t^o}Pb+H_2O\)
- Mol theo PTHH : \(1:1:1:1\)
- Mol theo phản ứng : \(0,04\rightarrow0,04\rightarrow0,04\rightarrow0,04\)
\(\Rightarrow m_{Pb}=n_{Pb}.M_{Pb}=0,04.207=8,28\left(g\right)\)
a, PT: \(Mg+H_2SO_{4\left(l\right)}\rightarrow MgSO_4+H_2\)
Ta có: \(n_{Mg}=\dfrac{12}{24}=0,5\left(mol\right)\)
Theo PT: \(n_{H_2}=n_{Mg}=0,5\left(mol\right)\)
\(\Rightarrow V_{H_2}=0,5.22,4=11,2\left(l\right)\)
b, PT: \(CuO+H_2\underrightarrow{t^o}Cu+H_2O\)
Theo PT: \(n_{Cu}=n_{H_2}=0,5\left(mol\right)\)
\(\Rightarrow m_{Cu}=0,5.64=32\left(g\right)\)
Bạn tham khảo nhé!