để đốt cháy hết 5,4 gam nhôm cần lấy bao nhiêu lít không khí đo ở đktc?
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
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)
![](https://rs.olm.vn/images/avt/0.png?1311)
nCH4 = 3,2/16 = 0,2 (mol)
PTHH: CH4 + 2O2 -> (t°) CO2 + 2H2O
Mol: 0,2 ---> 0,4
Vkk = 0,4 . 5 . 22,4 = 44,8 (l)
PTHH: CH4 + Cl2 -> CH3Cl + HCl
Mol: 0,2 ---> 0,2
mCl2 = 0,2 . 71 = 14,2 (g)
![](https://rs.olm.vn/images/avt/0.png?1311)
Số mol của 12 gam cacbon:
\(n_C=\dfrac{m}{M}=\dfrac{12}{12}=1\left(mol\right)\)
Thể tích của 1 mol O2:
\(V_{O_2\left(đktc\right)}=n.22,4=1.22,4=22,4\left(l\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) nAl=0,2(mol)
PTHH: 4Al +3 O2 -to-> 2 Al2O3
nO2=3/4. 0,2=0,15(mol)
=>V(O2,đktc)=0,15.22,4=3,36(l)
b) V(kk,đktc)=3,36.5=16,8(l)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{O_2}=\dfrac{6}{24}=0,25\left(mol\right)\\ 4Al+3O_2\underrightarrow{to}2Al_2O_3\\ n_{Al_2O_3}=\dfrac{10,2}{102}=0,1\left(mol\right)\\ Vì:\dfrac{0,25}{3}>\dfrac{0,1}{2}\\ \Rightarrow O_2dư\\ n_{O_2\left(p.ứ\right)}=\dfrac{3}{2}.0,1=0,15\left(mol\right)\\ n_{Al\left(p.ứ\right)}=\dfrac{4}{2}.0,1=0,2\left(mol\right)\\ a.m_{Al\left(p.ứ\right)}=0,2.27=5,4\left(g\right)\\ b.\%m_{O_2\left(dư\right)}=\%V_{O_2\left(dư\right)}=\%n_{O_2\left(dư\right)}=\dfrac{0,25-0,15}{0,15}.100\approx66,667\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(2C_2H_2+5O_2-^{t^o}\rightarrow4CO_2+2H_2O\\ n_{C_2H_2}=\dfrac{1,3}{26}=0,05\left(mol\right)\\ n_{O_2}=\dfrac{5}{2}n_{C_2H_2}=0,125\left(mol\right)\\ \Rightarrow V_{O_2}=2,8\left(l\right)\\ Vìtrongkhôngkhíchứa20\%O_2\\ \Rightarrow V_{kk}=\dfrac{2,8}{20\%}=14\left(l\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\)1.
\(n_{O_2}=\dfrac{13.44}{22.4}=0.6\left(mol\right)\)
\(4Al+3O_2\underrightarrow{^{^{t^0}}}2Al_2O_3\)
\(0.8........0.6..........0.4\)
\(m_{Al}=0.8\cdot27=21.6\left(g\right)\)
\(m_{Al_2O_3}=0.4\cdot102=40.8\left(g\right)\)
\(2KMnO_4\underrightarrow{^{^{t^0}}}K_2MnO_4+MnO_2+O_2\)
\(1.2..................................................0.6\)
\(m_{KMnO_4}=1.2\cdot158=189.6\left(g\right)\)
2.
\(n_{O_2}=\dfrac{28}{22.4}=1.25\left(mol\right)\)
\(4P+5O_2\underrightarrow{^{^{t^0}}}2P_2O_5\)
\(1......1.25........0.5\)
\(m_P=1\cdot31=31\left(g\right)\)
\(m_{P_2O_5}=0.5\cdot142=71\left(g\right)\)
\(2KClO_3\underrightarrow{^{^{t^0}}}2KCl+3O_2\)
\(\dfrac{5}{6}................1.25\)
\(m_{KClO_3}=\dfrac{5}{6}\cdot122.5=102.083\left(g\right)\)
\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
PTHH: 4Al + 3O2 --to--> 2Al2O3
0,2-->0,15
=> VO2 = 0,15.22,4 = 3,36 (l)
=> Vkk = 3,36.5 = 16,8 (l)