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Gọi hóa trị kim loại R cần tìm là \(x\) \(\left(x\in\left\{2;3;\dfrac{8}{3}\right\}\right)\)
PTHH: \(Zn+H_2SO_4\rightarrow ZnSO_4+H_2\uparrow\)
\(R_2O_x+xH_2\underrightarrow{t^o}2R+xH_2O\)
Ta có: \(\left\{{}\begin{matrix}n_{Zn}=\dfrac{19,5}{65}=0,3\left(mol\right)\\n_{H_2SO_4}=\dfrac{40}{98}=\dfrac{20}{49}\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\) H2SO4 còn dư, Zn phản ứng hết
\(\Rightarrow n_R=\dfrac{0,6}{x}\left(mol\right)\) \(\Rightarrow M_R=\dfrac{11,2}{\dfrac{0,6}{x}}=\dfrac{56x}{3}\)
Ta thấy \(x=3\) thì \(M_R=56\) nên kim loại cần tìm là Sắt
+) Công thức của oxit bazơ: Fe2O3
+) Gọi tên: Sắt (III) oxit
a) nFe= 5,6/56=0,1(mol)
nHCl=10,95/36,5=0,3(mol)
PTHH: Fe + 2 HCl -> FeCl2 + H2
Ta có: 0,3/2 > 0,1/1
=> HCl dư, Fe hết, tính theo nFe
-> nH2=nFeCl2=nFe=0,1(mol)
=> V(H2,đktc)=0,1.22,4=2,24(l)
mFeCl2=0,1.127=12,7(g)
\(n_{Fe}=\dfrac{5.6}{56}=0.1\left(mol\right)\)
\(n_{HCl}=\dfrac{10.95}{36.5}=0.3\left(mol\right)\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
Lập tỉ lệ :
\(\dfrac{0.2}{1}>\dfrac{0.3}{2}\Rightarrow Fedư\)
Khi đó :
\(n_{FeCl_2}=n_{H_2}=\dfrac{1}{2}\cdot n_{HCl}=\dfrac{1}{2}\cdot0.3=0.15\left(mol\right)\)
\(m_{FeCl_2}=0.15\cdot127=19.05\left(g\right)\)
\(V_{H_2}=0.15\cdot22.4=3.36\left(l\right)\)
\(n_{Fe}=\dfrac{5,6}{56}=0,1\left(mol\right)\\ n_{HCl}=\dfrac{10,95}{36,5}=0,3\left(mol\right)\\ PTHH:Fe+2HCl\rightarrow FeCl_2+H_2\\ Vì:\dfrac{0,1}{1}< \dfrac{0,3}{2}\\ \Rightarrow HCldư\\ \Rightarrow n_{FeCl_2}=n_{Fe}=n_{H_2}=0,1\left(mol\right)\\ \Rightarrow m_{FeCl_2}=127.0,1=12,7\left(g\right)\\ V_{H_2\left(đktc\right)}=0,1.22,4=2,24\left(l\right)\)
`Fe + 2HCl -> FeCl_2 + H_2`
`0,2` `0,2` `0,2` `(mol)`
`n_[Fe]=[11,2]/56=0,2(mol)`
`a)m_[FeCl_2]=0,2.127=25,4(g)`
`b)V_[H_2]=0,2.22,4=4,48(l)`
`c)n_[O_2]=[4,48]/[22,4]=0,2(mol)`
`2H_2 + O_2` $\xrightarrow{t^o}$ `2H_2 O`
`0,2` `0,1` `0,2` `(mol)`
Ta có:`[0,2]/2 < [0,2]/1`
`=>O_2` dư
`=>m_[H_2 O]=0,2.18=3,6(g)`
\(\begin{array} {l} a)\\ Fe+2HCl\to FeCl_2+H_2\\ n_{Fe}=\dfrac{11,2}{56}=0,2(mol)\\ n_{FeCl_2}=n_{Fe}=0,2(mol)\\ m_{FeCl_2}=0,2.127=25,4(g)\\ b)\\ n_{H_2}=n_{Fe}=0,2(mol)\\ V_{H_2}=0,2.22,4=4,48(l)\\ c)\\ n_{O_2}=\dfrac{4,48}{22,4}=0,2(mol)\\ 2H_2+O_2\xrightarrow{t^o}2H_2O\\ \dfrac{n_{H_2}}{2}<n_{O_2}\to O_2\text{ dư}\\ n_{H_2O}=n_{H_2}=0,2(mol)\\ m_{H_2O}=0,2.18=3,6(g) \end{array}\)
a: \(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(n_{Fe}=\dfrac{11.2}{56}=0.2\left(mol\right)\)
nên \(n_{FeCl_2}=0,2\left(mol\right)\)
\(m_{FeCl_2}=0.2\cdot127=25,4\left(g\right)\)
b: \(V_{H_2}=0.2\cdot22.4=4.48\left(lít\right)\)
a,\(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\)
PTHH: Zn + 2HCl ---> ZnCl2 + H2
0,1--------------->0,1------>0,1
b, => \(\left\{{}\begin{matrix}C_{M\left(ZnCl_2\right)}=\dfrac{0,1}{\dfrac{6}{1000}}=\dfrac{50}{3}M\\V_{H_2}=0,1.22,4=2,24\left(l\right)\end{matrix}\right.\)
c, \(n_{O_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)
PTHH: 2H2 + O2 --to--> 2H2O
LTL: \(\dfrac{0,1}{2}< 0,1\)=> O2 dư
Theo pt: \(n_{O_2}=\dfrac{1}{2}n_{H_2}=\dfrac{1}{2}.0,1=0,05\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}m_{O_2\left(dư\right)}=\left(0,1-0,05\right).32=1,6\left(g\right)\\V_{O_2\left(dư\right)}=\left(0,1-0,05\right).22,4=1,12\left(l\right)\end{matrix}\right.\)
\(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\\ n_{HCl}=\dfrac{36,5}{36,5}=1\left(mol\right)\\ Zn+2HCl\rightarrow ZnCl_2+H_2\\a, V\text{ì}:\dfrac{0,1}{1}< \dfrac{1}{2}\Rightarrow HCl\text{dư}\\ n_{HCl\left(d\text{ư}\right)}=1-0,1.2=0,8\left(mol\right)\\ m_{HCl\left(d\text{ư}\right)}=0,8.36,5=29,2\left(g\right)\\ b,n_{ZnCl_2}=n_{Zn}=0,1\left(mol\right)\\ m_{ZnCl_2}=136.0,1=13,6\left(g\right)\)
\(Zn + 2HCl \to ZnCl_2 + H_2\)
Theo PTHH : \(n_{H_2} = n_{Zn} = \dfrac{6,5}{65} = 0,1(mol)\)
\(Fe_3O_4 + 4H_2 \xrightarrow{t^o} 3Fe + 4H_2O\)
Ta có :
\(n_{Fe} = \dfrac{3}{4}n_{H_2} = 0,075(mol)\\ \Rightarrow m_{Fe} = 0,075.56 = 4,2(gam)\)