đốt cháy một lượng sắt tạo thành 46,4 gam sắt từ oxit Fe3O4. ( Fe=56, Al=27, O=16). Tính
a) thể tích khí oxi cần dùng ở đktc
b) khối lượng sắt ban đầu
*c) khối lượng nhôm cần dùng để tác dụng hết lượng khí oxi trên
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Bài 3:
Ta có: \(n_{Fe_2O_3}=\dfrac{32}{160}=0,2\left(mol\right)\)
PT: \(Fe_2O_3+3H_2\underrightarrow{t^o}2Fe+3H_2O\)
_____0,2____0,6____0,4 (mol)
\(\Rightarrow V_{H_2}=0,6.22,4=13,44\left(l\right)\)
\(m_{Fe}=0,4.56=22,4\left(g\right)\)
Bài 4:
a, \(n_P=\dfrac{6,2}{31}=0,2\left(mol\right)\)
\(n_{O_2}=\dfrac{7,84}{22,4}=0,35\left(mol\right)\)
PT: \(4P+5O_2\underrightarrow{t^o}2P_2O_5\)
Xét tỉ lệ: \(\dfrac{0,2}{4}< \dfrac{0,35}{5}\), ta được O2 dư.
Theo PT: \(n_{O_2\left(pư\right)}=\dfrac{5}{4}n_P=0,25\left(mol\right)\Rightarrow n_{O_2\left(dư\right)}=0,35-0,25=0,1\left(mol\right)\)
\(\Rightarrow m_{O_2\left(dư\right)}=0,1.32=3,2\left(g\right)\)
b, Theo PT: \(n_{P_2O_5}=\dfrac{1}{2}n_P=0,1\left(mol\right)\Rightarrow m_{P_2O_5}=0,1.142=14,2\left(g\right)\)
Lần sau bạn nên chia nhỏ câu hỏi ra nhé.
Bài 1:
a, \(n_{Fe}=\dfrac{16,8}{56}=0,3\left(mol\right)\)
PT: \(3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
Theo PT: \(n_{O_2}=\dfrac{2}{3}n_{Fe}=0,2\left(mol\right)\Rightarrow V_{H_2}=0,2.22,4=4,48\left(l\right)\)
b, \(2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\)
\(n_{KMnO_4}=2n_{O_2}=0,4\left(mol\right)\Rightarrow m_{KMnO_4}=0,4.158=63,2\left(g\right)\)
Bài 2:
a, \(n_{Al}=\dfrac{2,7}{27}=0,1\left(mol\right)\)
PT: \(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
_____0,1___________0,1_____0,15 (mol)
\(m_{AlCl_3}=0,1.133,5=13,35\left(g\right)\)
\(V_{H_2}=0,15.22,4=3,36\left(l\right)\)
b, PT: \(CuO+H_2\underrightarrow{t^o}Cu+H_2O\)
Theo PT: \(n_{CuO}=n_{H_2}=0,15\left(mol\right)\Rightarrow m_{CuO}=0,15.80=12\left(g\right)\)
a. \(n_{Fe_3O_4}=\dfrac{6,96}{232}=0,03\left(mol\right)\)
PTHH : 3Fe + 2O2 -to-> Fe3O4
0,09 0,06 0,03
\(m_{Fe}=0,09.56=5,04\left(g\right)\)
\(V_{O_2}=0,06.22,4=1,344\left(l\right)\)
b. PTHH : 2KCl + 3O2 -> 2KClO3
0,06 0,04
\(m_{KClO_3}=0,04.122,5=4,9\left(g\right)\)
\(n_{Fe}=\dfrac{8,4}{56}=0,15\left(mol\right)\\ pthh:3Fe+2O_2\underrightarrow{t^o}Fe_3O_{\text{4}}\)
0,15 0,1 0,05
\(m_{Fe_2O_4}=0,05.232=11,6\left(g\right)\\
V_{O_2}=0,1.11,4=2,24\left(l\right)\\
pthh:2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\uparrow\)
0,2 0,1
\(m_{KMnO_4}=0,2.158=31,6\left(g\right)\)
\(n_{Fe}=\dfrac{8,4}{56}=0,15\left(mol\right)\\ pthh:3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
0,15 0,1 0,05
\(m_{Fe_3O_{\text{ 4}}}=0,05.232=11,6\left(g\right)\\ V_{O_2}=0,1.22,4=2,24\left(l\right)\\ pthh:2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\)
0,1 0,05
\(m_{KMnO_4}=0,1.158=15,8\left(g\right)\)
Bài 1:
PT: \(3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
a, Ta có: \(n_{Fe}=\dfrac{5,6}{56}=0,1\left(mol\right)\)
\(n_{O_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
Xét tỉ lệ: \(\dfrac{0,1}{3}< \dfrac{0,1}{2}\), ta được O2 dư.
Theo PT: \(n_{O_2\left(pư\right)}=\dfrac{2}{3}n_{Fe}=\dfrac{1}{15}\left(mol\right)\)
\(\Rightarrow n_{O_2\left(dư\right)}=0,1-\dfrac{1}{15}=\dfrac{1}{30}\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}m_{O_2\left(dư\right)}=\dfrac{1}{30}.32\approx1,067\left(g\right)\\V_{O_2\left(dư\right)}=\dfrac{1}{30}.2,24\approx0,746\left(l\right)\end{matrix}\right.\)
b, Theo PT: \(n_{Fe_3O_4}=\dfrac{1}{3}n_{Fe}=\dfrac{1}{30}\left(mol\right)\)
\(\Rightarrow m_{Fe_3O_4}=\dfrac{1}{30}.232\approx7,733\left(g\right)\)
Bài 2:
PT: \(3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
a, Ta có: \(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)
Theo PT: \(n_{Fe_3O_4}=\dfrac{1}{3}n_{Fe}=\dfrac{1}{15}\left(mol\right)\)
\(\Rightarrow m_{Fe_3O_4}=\dfrac{1}{15}.232\approx15,467\left(g\right)\)
b, Theo PT: \(n_{O_2}=\dfrac{2}{3}n_{Fe}=\dfrac{2}{15}\left(mol\right)\)
\(\Rightarrow V_{O_2}=\dfrac{2}{15}.22,4\approx2,9867\left(l\right)\)
c, PT: \(2N_2+5O_2\underrightarrow{t^o}2N_2O_5\)
Ta có: \(n_{N_2}=\dfrac{2,8}{28}=0,1\left(mol\right)\)
Xét tỉ lệ: \(\dfrac{0,1}{2}>\dfrac{\dfrac{2}{15}}{5}\), ta được N2 dư.
Theo PT: \(n_{N_2O_5}=\dfrac{2}{5}n_{O_2}=\dfrac{4}{75}\left(mol\right)\)
\(\Rightarrow m_{N_2O_5}=\dfrac{4}{75}.108=5,76\left(g\right)\)
Bạn tham khảo nhé!
Bài 1 :
\(n_{Fe}=\dfrac{5.6}{56}=0.1\left(mol\right)\)
\(n_{O_2}=\dfrac{2.24}{224}=0.1\left(mol\right)\)
\(3Fe+2O_2\underrightarrow{t^0}Fe_3O_4\)
\(Bđ:0.1......0.1\)
\(Pư:0.1.......\dfrac{1}{15}...\dfrac{1}{30}\)
\(Kt:0........\dfrac{1}{30}....\dfrac{1}{30}\)
\(V_{O_2\left(dư\right)}=\dfrac{1}{30}\cdot22.4=0.747\left(l\right)\)
\(m_{Fe_3O_4}=\dfrac{1}{30}\cdot232=7.73\left(g\right)\)
Bài 2 :
\(n_{Fe}=\dfrac{11.2}{56}=0.2\left(mol\right)\)
\(3Fe+2O_2\underrightarrow{t^0}Fe_3O_4\)
\(0.2.......0.3.......\dfrac{1}{15}\)
\(V_{O_2}=0.3\cdot22.4=6.72\left(l\right)\)
\(m_{Fe_3O_4}=\dfrac{1}{15}\cdot232=15.47\left(g\right)\)
\(n_{N_2}=\dfrac{2.8}{28}=0.1\left(mol\right)\)
\(2N_2+5O_2\underrightarrow{t^0}2N_2O_5\)
\(0.12......0.3........0.12\)
\(m_{N_2O_5}=0.12\cdot108=12.96\left(g\right)\)
Bài 3 :
PTHH : \(6Fe+4O_2\left(t^o\right)->2Fe_3O_4\) (1)
\(n_{Fe_3O_4}=\dfrac{m}{M}=\dfrac{2,32}{56.3+16.4}=0,01\left(mol\right)\)
Từ (1) => \(3n_{Fe_3O_4}=n_{Fe}=0,03\left(mol\right)\)
=> \(m_{Fe}=n.M=1,68\left(g\right)\)
Từ (1) => \(2n_{Fe_3O_4}=n_{O_2}=0,02\left(mol\right)\)
=> \(V_{O_2\left(đktc\right)}=n.22,4=0,448\left(l\right)\)
Bài 4 :
PTHH : \(4P+5O_2\left(t^o\right)->2P_2O_5\) (1)
\(n_P=\dfrac{m}{M}=\dfrac{6,2}{31}=0,2\left(mol\right)\)
\(n_{O_2}=\dfrac{V}{22,4}=\dfrac{6,72}{32}=0,21\left(mol\right)\)
Có : \(n_P< n_{O_2}\left(0,2< 0,21\right)\)
-> P hết ; O2 dư
Từ (1) -> \(\dfrac{1}{2}n_P=n_{P_2O_5}=0,1\left(mol\right)\)
=> \(m_{P_2O_5}=n.M=14,2\left(g\right)\)
Bài 3:
\(n_{Fe_3O_4}=\dfrac{2,32}{232}=0,01\left(mol\right)\)
PTHH: 3Fe + 2O2 ---to→ Fe3O4
Mol: 0,03 0,02 0,01
\(m_{Fe}=0,03.56=1,68\left(g\right);V_{O_2}=0,02.22,4=0,448\left(l\right)\)
nFe = 46,4/56 = 29/35 (mol)
PTHH: 4Fe + 3O2 -> (t°) 2Fe2O3
Mol: 29/35 ---> 87/140 ---> 29/70
mFe2O3 = 29/70 . 160 = 464/7 (g)
Vkk = 87/140 . 5 . 22,4 = 69,6 (l)
a) \(n_{Fe}=\dfrac{3,36}{56}=0,06\left(mol\right)\)
PTHH: 3Fe + 2O2 --to--> Fe3O4
0,06->0,04------->0,02
=> mFe3O4 = 0,02.232 = 4,64 (g)
b) VO2 = 0,04.22,4 = 0,896 (l)
a. \(n_{Fe}=\dfrac{16,8}{56}=0,3\left(mol\right)\)
PTHH : 3Fe + 2O2 -to> Fe3O4
0,3 0,2 0,1
b. \(m_{Fe_3O_4}=0,1.232=23,2\left(g\right)\)
c. \(V_{O_2}=0,2.22,4=4,48\left(l\right)\)
a \(3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
b \(\Rightarrow n_{Fe}=\dfrac{16,8}{56}=0,3mol\) \(\Rightarrow n_{Fe_3O_4}=\dfrac{1}{3}n_{Fe}=0,1mol\Rightarrow m_{Fe_3O_4}=0,1\cdot232=2,32g\)
c \(\Rightarrow n_{O_2}=\dfrac{2}{3}n_{Fe}=0,2mol\Rightarrow V_{O_2}=0,2\cdot22,4=4,48l\)
\(n_{Fe}=\dfrac{1,68}{56}=0,03\left(mol\right)\)
\(3Fe+2O_2\rightarrow\left(t^o\right)Fe_3O_4\)
0,03 0,02 0,01 ( mol )
\(m_{Fe_3O_4}=0,01.232=2,32\left(g\right)\)
\(V_{kk}=0,02.22,4.5=2,24\left(l\right)\)
\(2KClO_3\rightarrow\left(t^o\right)2KCl+3O_2\)
\(\dfrac{1}{75}\) 0,02 ( mol )
\(m_{KClO_3}=\dfrac{1}{75}.122,5=1,63\left(g\right)\)
a,nFe=1,68/56=0,03 mol
Ta có PTHH : 3Fe + 2O2 --> Fe3O4 (1) ( ở trên dấu --> có to nha )
Theo PTHH ta có :
nFe3O4=1/3nFe=1/3.0,03=0,01 mol
nO2=2/3nFe=2/3.0,03=0,02 mol
=>mFe3O4= 0,01.232=2,32g
=>Vkk=5.(0,02.22,4)=2,24 l
b, Ta có PTHH: 2KClO3 --> 2KCl + 3O2 (2) ( trên dấu --> vẫn có to )
Gọi x là số mol KClO3 cần dùng ( x > 0 )
Theo PTHH (3) và theo bài ra ta có PTHH sau:
2/3x=0,02
=> x=0,03 mol
=> mKClO3= 0,03.122,5= 3,675g
3Fe + 2O2 -> Fe3O4
a) nFe = \(\dfrac{46,4}{56}=0,82\left(mol\right)\)
=> \(n_{O_2}=\dfrac{2}{3}n_{Fe}=\dfrac{2}{3}.0,82=0,54\left(mol\right)\)
=> VO2 = 0,54 . 22,4 = 12,096(l)
b) mFe = 0,82 . 56 = 45,92 (g)
c) 4Al + 3O2 -> 2Al2O3
Theo PTHH: \(n_{Al}=\dfrac{4}{3}n_{O_2}=\dfrac{4}{3}.0,54=0,72\left(mol\right)\)
=> mAl = 0,72 . 27 = 19,44 (g).
PTHH:3Fe+2O2----->Fe3O4
a.\(n_{Fe_3O_4}=\dfrac{m_{Fe_3O_4}}{M_{Fe_3O_4}}=\dfrac{46,4}{232}=0,2\left(mol\right)\)
Theo PTHH:\(n_{O_2}=2n_{Fe_3O_4}=2.0,2=0,4\left(mol\right)\)
\(V_{O_2}=n_{O_2}.22,4=0,4.22,4=8,96\left(l\right)\)
b.Theo PTHH:\(n_{Fe}=3n_{Fe_3O_4}=3.0,2=0,6\left(mol\right)\)
\(m_{Fe}=n_{Fe}.M_{Fe}=0,6.56=33,6\left(g\right)\)
c.PTHH:4Al+3O2----->2Al2O3
Theo PTHH:\(n_{Al}=\dfrac{4}{3}n_{O_2}=\dfrac{4}{3}.0,4=\dfrac{8}{15}\left(mol\right)\)
\(m_{Al}=n_{Al}.M_{Al}=\dfrac{8}{15}.27=14,4\left(g\right)\)