Tiến hành nhiệt phân m(g) KMnO4 thu được 5,6 lít khí O2 đktc . Tìm m biêdt hao hụt trong quá trình sản xuất là 20 %
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câu 5
nKMnO4=\(\dfrac{31,6.98\%}{158}\)=0,196(mol)
2KMnO4−to→K2MnO4+MnO2+O2
nO2(lt)=\(\dfrac{1}{2}\)nKMnO4=0,098(mol)
Vìhaohụt5%
⇒VO2(tt)=0,098.95%.22,4=2,08544(l)
2KClO3-to>2KCl+3O2
0,08--------------------0,12 mol
n O2=2,688\22,4=0,12 mol
H=20%
=>m KClO3tt=0,08.122,5.100\20=49g
\(n_{O_2}=\dfrac{2,688}{22,4}=0,12\left(mol\right)\\ 2KClO_3\underrightarrow{^{to}}2KCl+3O_2\\ n_{KClO_3\left(LT\right)}=\dfrac{2}{3}.0,12=0,08\left(mol\right)\\ Hao.hụt.80\%.Nên:n_{KClO_3\left(TT\right)}=0,08:\left(100\%-20\%\right)=0,1\left(mol\right)\\\Rightarrow m=m_{KClO_3\left(TT\right)}=122,5.0,1=12,25\left(g\right)\)
nO2 = \(\dfrac{6,72}{22,4}=0,3\left(mol\right)\)
pt: \(2KMnO_4\rightarrow K_2MnO_4+MnO_2+O_2\)
Theo pt: \(n_{KMnO_4}=2n_{O_2}=0,6mol\)
=> nKMnO4 thực tế = 0,6:\(\dfrac{90}{100}=\dfrac{2}{3}\left(mol\right)\)
mKMnO4 = \(\dfrac{2}{3}.158=\dfrac{316}{3}g\)
\(m_{KMnO_4}=31,6.98\%=30,968g\)
\(m_{KMnO_4}=30,968.95\%=29,4196g\)
\(n_{KMnO_4}=\dfrac{m_{KMnO_4}}{M_{KMnO_4}}=\dfrac{29,4196}{158}=0,1862mol\)
\(2KMnO_4\rightarrow\left(t^o\right)K_2MnO_4+MnO_2+O_2\)
0,1862 0,0931 ( mol )
\(V_{O_2}=n_{O_2}.22,4=0,0931.22,4=2,08544l\)
\(n_{KMnO_4}=\dfrac{31,6.98\%}{158}=0,196\left(mol\right)\\ 2KMnO_4-^{t^o}\rightarrow K_2MnO_4+MnO_2+O_2\\ n_{O_2\left(lt\right)}=\dfrac{1}{2}n_{KMnO_4}=0,098\left(mol\right)\\ Vìhaohụt5\%\\ \Rightarrow V_{O_2\left(tt\right)}=0,098.95\%.22,4=2,08544\left(l\right)\)
\(n_{Al}=\dfrac{5.4}{27}=0,2mol\)
\(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)
0,2 0,15 0,1
a)\(V_{O_2}=0,15\cdot22,4=3,36l\)
b)\(n_{O_2}=0,15\cdot10\%=0,015mol\)
\(2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\)
0,03 0,015
\(m_{KMnO_4}=0,03\cdot158=4,74g\)
PTHH: \(2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\uparrow\)
a) Ta có: \(n_{KMnO_4}=\dfrac{94,8}{158}=0,6\left(mol\right)\)
\(\Rightarrow n_{O_2\left(lýthuyết\right)}=0,3\left(mol\right)\) \(\Rightarrow n_{O_2\left(thực\right)}=0,3\cdot90\%=0,27\left(mol\right)\)
\(\Rightarrow V_{O_2\left(thực\right)}=0,27\cdot22,4=6,048\left(l\right)\)
b) PTHH: \(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)
Theo PTHH: \(n_{Al_2O_3}=\dfrac{2}{3}n_{O_2}=0,18\left(mol\right)\)
\(\Rightarrow m_{Al_2O_3}=0,18\cdot102=18,36\left(g\right)\)
b.
Rắn A gồm: KMnO4, K2MnO4, MnO2
2KMnO4 + 16HCl → 2KCl + 2MnCl2 + 5Cl2 ↑+ 8H2O
K2MnO4 + 8HCl → 2KCl + MnCl2 + 2Cl2↑ + 4H2O
MnO2 + 4HCl → MnCl2 + Cl2↑ + 2H2O
Vậy khí B là Cl2.
a)nO2=\(\dfrac{3.36}{22.4}\)=0,15(mol)
2KMnO4(to)→K2MnO4+MnO2+O2
Theo PT: nKMnO4=2nO2=0,3(mol)
→m=mKMnO4=0,3.158=47,4(g)
b)nH2=\(\dfrac{8.96}{22.4}\)=0,4(mol)
2H2+O2(to)→2H2O
Vì \(\dfrac{nH_2}{2}\)<nO2→O2nH2 dư
Theo PT: nH2O=nH2=0,4(mol)
→mH2O=0,4.18=7,2(g)
2KMnO4-to>K2MnO4+MnO2+O2
0,5------------------------------------0,25
n O2=5,6\22,4=0,25 mol
=>m KMnO4=0,5.158.20\100=12,8g