thể tích khí 02 ở đktc cần thiết để đốt cháy hết 5,4(g) bột Al
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Bài 1 :
\(n_{Na}=\dfrac{m}{M}=0,1\left(mol\right)\)
\(4Na+O_2\rightarrow2Na_2O\)
..0,1....0,025....0,05.......
a, \(V_{O_2}=n.22,4=0,56\left(l\right)\)
b, \(m=m_{Na_2o}=n.M=3,1\left(g\right)\)
Bài 2 :
\(n_{Al}=\dfrac{m}{M}=0,1\left(mol\right)\)
\(4Al+3O_2\rightarrow2Al_2O_3\)
..0,1...0,075...
\(\Rightarrow n_{O_2}=0,075\left(mol\right)\)
Mà : \(\Sigma n_{O_2}=\dfrac{V}{22,4}=0,4\left(mol\right)\)
\(\Rightarrow n_{O_2\left(Mg\right)}=0,4-0,075=0,325\left(mol\right)\)
\(2Mg+O_2\rightarrow2MgO\)
.0,65.....0,325........
\(\Rightarrow m_{Mg}=15,6\left(g\right)\)
\(\Rightarrow m_{hh}=2,7+15,6=18,3\left(g\right)\)
\(\Rightarrow\left\{{}\begin{matrix}\%Al=~14,75\\\%Mg=~85,25\end{matrix}\right.\) %
Bài 3 :
- Gọi số mol Al và Mg lần lượt là x , y
\(4Al+3O_2\rightarrow2Al_2O_3\)
..x....0,75x
\(2Mg+O_2\rightarrow2MgO\)
..y........0,5y...........
Có : \(n_{O_2}=0,75x+0,5y=\dfrac{V}{22,4}=0,1\left(mol\right)\left(I\right)\)
Lại có : \(m_{hh}=m_{Al}+m_{Mg}=27x+24y=3,9\left(II\right)\)
- Giair ( i ) và ( ii ) ta được : \(\left\{{}\begin{matrix}x=0,1\\y=0,05\end{matrix}\right.\) ( mol )
\(\Rightarrow\left\{{}\begin{matrix}\%Al=~69,23\\\%Mg=~30,77\end{matrix}\right.\) %
Vậy ...
a) \(n_{Al_2O_3}=\dfrac{20,4}{102}=0,2\left(mol\right)\)
PTHH: 4Al + 3O2 --to--> 2Al2O3
0,4<--0,3<---------0,2
=> mAl = 0,4.27 = 10,8(g)
b) C1: VO2 = 0,3.22,4 = 6,72(l)
C2: Theo ĐLBTKL: mO2 = 20,4 - 10,8 = 9,6(g)
=> \(n_{O_2}=\dfrac{9,6}{32}=0,3\left(mol\right)=>V_{O_2}=0,3.22,4=6,72\left(l\right)\)
c) Vkk = 6,72 : 20% = 33,6(l)
a) $n_{Al} = \dfrac{5,4}{27} = 0,2(mol)$
$4Al + 3O_2 \xrightarrow{t^o} 2Al_2O_3$
Theo PTHH : $n_{O_2} = \dfrac{3}{4}n_{Al} = 0,15(mol)$
$V_{O_2} = 0,15.22,4 = 3,36(lít)$
b) $2 KClO_3 \xrightarrow{t^o} 2KCl + 3O_2$
$n_{KClO_3} = \dfrac{2}{3}n_{O_2} = 0,1(mol)$
$m_{KClO_3} = 0,1.122,5 = 12,25(gam)$
\(n_{Al}=\dfrac{m}{M}=\dfrac{5,4}{27}=0,2\left(mol\right)\\ PTHH:4Al+3O_2-^{t^o}>2Al_2O_3\)
tỉ lệ: 4 : 3 : 2
n(mol) 0,2---->0,15---->0,1
\(V_{O_2\left(dktc\right)}=n\cdot22,4=0,15\cdot22,4=3,36\left(l\right)\\ PTHH:2KClO_3-^{t^o}>2KCl+3O_2\)
tỉ lệ: 2 : 2 : 3
n(mol) 0,1<-------------------------0,15
\(m_{KClO_3}=n\cdot M=0,1\cdot\left(39+35,5+16\cdot3\right)=12,25\left(g\right)\)
\(n_{O2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\)
Pt : \(S+O_2\underrightarrow{t^o}SO_2|\)
1 1 1
0,15 0,15 0,15
a) \(n_S=\dfrac{0,15.1}{1}=0,15\left(mol\right)\)
⇒ \(m_S=0,15.32=4,8\left(g\right)\)
b) \(n_{SO2}=\dfrac{0,15.1}{1}=0,15\left(mol\right)\)
\(V_{SO2\left(dktc\right)}=0,15.22,4=3,36\left(l\right)\)
Chúc bạn học tốt
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
Theo PTHH: \(n_{AlCl_3}=n_{Al}=0,2\left(mol\right)\)
\(\Rightarrow m_{AlCl_3}=0,2.133,5=26,7\left(g\right)\)
Theo PTHH: \(n_{H_2}=\dfrac{0,2.3}{2}=0,3\left(mol\right)\)
\(\Rightarrow V_{H_2}=0,3.22,4=6,72\left(l\right)\)
\(n_{CH_4}=\dfrac{3,2}{16}=0,2\left(mol\right)\)
PTHH: CH4 + 2O2 ---to→ CO2 + 2H2O
Mol: 0,2 0,4
\(V_{O_2}=0,4.22,4=8,96\left(l\right)\)
\(CH_4+ZO_2\rightarrow CO_2+2H_2O\)
0,2 0,4 0,2
\(n_{CH_4}=\dfrac{m}{M}=\dfrac{3,2}{16}=0,2\left(mol\right)\)
\(\Rightarrow V_{O_2}=8,96l\\ m_{CO_2}=n.M=0,2.44=8,8\left(g\right)\)
a) \(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
PTHH: 4Al + 3O2 --to--> 2Al2O3
0,2-->0,15
=> V = 0,15.22,4 = 3,36 (l)
b)
PTHH: 2KMnO4 --to--> K2MnO4 + MnO2 + O2
0,3<----------------------------0,15
=> mKMnO4(lý thuyết) = 0,3.158 = 47,4 (g)
=> \(m_{KMnO_4\left(tt\right)}=\dfrac{47,4.110}{100}=52,14\left(g\right)\)
\(a) n_{Al} = \dfrac{5,4}{27} = 0,2(mol)\\ 4Al + 3O_2 \xrightarrow{t^o} 2Al_2O_3\\ n_{O_2} = \dfrac{3}{4}n_{Al} = 0,15(mol)\\ \Rightarrow V_{O_2} = 0,15.22,4 = 3,36(lít)\\ b)C_3H_4 + 4O_2 \xrightarrow{t^o} 3CO_2 + 2H_2O\\ V_{O_2} = 4V_{C_3H_4} = 11,2.4 = 44,8(lít)\)
a, \(n_{Al}=\dfrac{m}{M}=0,2\left(mol\right)\)
\(4Al+3O_2\rightarrow2Al_2O_3\)
..0,2..0,15........
\(\Rightarrow V_{O_2}=n.22,4=3,36\left(l\right)\)
b, ( mk nghĩ đề là CH4 :VVV )
\(n_{CH_4}=\dfrac{V}{22,4}=0,5\left(mol\right)\)
\(CH_4+2O_2\rightarrow CO_2+2H_2O\)
.0,5......1...............
\(\Rightarrow V_{O_2}=n.22,4=22,4\left(l\right)\)
\(n_{Al}=\frac{m}{M}=\frac{5,4}{27}=0,2\left(mol\right)\)
Có pt hóa học:
\(4Al+3O_2\rightarrow2Al_2O_3\)
\(0,2\rightarrow\)\(0,15\) \(0,1\) \(\left(mol\right)\)
\(V_{O_2}=n\cdot22,4=0,15\cdot22,4=3,36\left(l\right)\)
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