Cho 4g CuO tác dụng với 100g dung dịch HCl 2,92%
a.CÂN BẰNG PTHH
b. Tính khối lượng các chất sau phản ứng
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nHCl= (7,3%.250)/100=0,5(mol)
nCuO=0,05(mol)
a) PTHH: CuO +2 HCl -> CuCl2 + H2O
Ta có: 0,5/2 > 0,05/1
=> HCl dư, CuO hết => tính theo nCuO
b) nCuCl2=nCuO=0,05(mol) => mCuCl2= 135. 0,05= 6,75(g)
c) nHCl(dư)=0,5-0,05.2=0,4(mol) => mHCl(dư)=0,4.36,5=14,6(g)
mddsau=250+4= 254(g)
=>C%ddCuCl2= (6,75/254).100=2,657%
C%ddHCl(dư)= (14,6/254).100=5,748%
nCuO=16/80=0,2(mol)
a) PTHH: CuO + H2SO4 -> CuSO4 + H2O
0,2___________0,2_____0,2(mol)
b) mCuSO4=160.0,2=32(g)
c) mH2SO4=0,2.98=19,6(g)
=>C%ddH2SO4= (19,6/100).100=19,6%
\(a)ZnO+2HCl\rightarrow ZnCl_2+H_2O\\ b)n_{ZnO}=\dfrac{8,1}{81}=0,1mol\\ n_{HCl}=\dfrac{300.3,65}{100.36,5}=0,3mol\\ \Rightarrow\dfrac{0,1}{1}< \dfrac{0,3}{2}\Rightarrow HCl.dư\\ ZnO+2HCl\rightarrow ZnCl_2+H_2O\)
0,1 0,2 0,1 0,1
\(m_{ZnCl_2}=0,1.136=13,6g\\ m_{HCl.dư}=\left(0,3-0,2\right).36,5=3,65g\\ m_{H_2O}=0,1.18=1,8g\\ c)C_{\%ZnCl_2}=\dfrac{13,6}{8,1+300}\cdot100=4,41\%\\ C_{\%HCl.dư}=\dfrac{3,65}{8,1+300}\cdot100=1,18\%\)
\(n_{ZnO}=\dfrac{8,1}{81}=0,1\left(mol\right)\)
\(m_{HCl}=3,65\%.300=10,95\left(g\right)\Rightarrow n_{HCl}=\dfrac{10,95}{36,5}=0,3\left(mol\right)\)
a) PTHH : \(ZnO+2HCl\rightarrow ZnCl_2+H_2O\)
0,1 0,3 0,1
b) Xét tỉ lệ : \(\dfrac{0,1}{1}< \dfrac{0,3}{2}\Rightarrow HCldư\)
Sau phản ứng gồm có : ZnCl2 và dd HCl dư
\(m_{ZnCl2}=0,1.136=13,6\left(g\right)\)
\(m_{HCl\left(dư\right)}=\left(0,3-0,1.2\right).36,5=3,65\left(g\right)\)
c) \(m_{ddspu}=8,1+300=308,1\left(g\right)\)
\(C\%_{ddHCldư}=\dfrac{3,65}{308,1}.100\%=1,18\%\)
\(C\%_{ZnCl2}=\dfrac{13,6}{308,1}.100\%=4,41\%\)
a. Ta có: \(n_{Fe_3O_4}=\dfrac{23,2}{232}=0,1\left(mol\right)\)
Ta lại có: \(C_{\%_{HCl}}=\dfrac{m_{ct_{HCl}}}{100}.100\%=7,3\%\)
=> mHCl = 7,3(g)
=> \(n_{HCl}=\dfrac{7,3}{36,5}=0,2\left(mol\right)\)
PTHH:
Fe3O4 + 8HCl ---> FeCl2 + 2FeCl3 + 4H2O
1 ---> 8
0,1 ---> 0,2
=> \(\dfrac{0,1}{1}>\dfrac{0,2}{8}\)
Vậy Fe3O4 dư
=> mdư = 23,2 - 7,3 = 15,9 (g)
b. Theo PT: \(n_{FeCl_2}=\dfrac{1}{8}.n_{HCl}=\dfrac{1}{8}.0,2=0,025\left(mol\right)\)
=> \(m_{FeCl_2}=0,025.127=3,175\left(g\right)\)
Theo PT: \(n_{FeCl_3}=\dfrac{1}{4}.n_{HCl}=\dfrac{1}{4}.0,2=0,05\left(mol\right)\)
=> \(m_{FeCl_3}=0,05.162,5=8,125\left(g\right)\)
=> \(m_{muối}=8,125+3,175=11,3\left(g\right)\)
c. Ta có: mdung dịch sau PỨ = \(23,2+100=123,2\left(g\right)\)
Theo PT: \(n_{H_2O}=\dfrac{1}{2}.n_{HCl}=\dfrac{1}{2}.0,2=0,1\left(mol\right)\)
=> \(m_{H_2O}=0,1.18=1,8\left(g\right)\)
mcác chất sau PỨ = 1,8 + 11,3 = 13,1(g)
=> \(C_{\%_{sauPỨ}}=\dfrac{13,1}{123,2}.100\%=10,63\%\)
\(a) CuO + 2HCl \to CuCl_2 + H_2O\\ b) n_{CuO} = \dfrac{4,8}{80} = 0,06(mol) ; n_{HCl} = \dfrac{100.3,65\%}{36,5} = 0,1(mol)\\ \dfrac{n_{CuO}}{1}= 0,06 > \dfrac{n_{HCl}}{2} = 0,05 \to CuO\ dư\\ n_{CuCl_2} = n_{CuO\ pư} = \dfrac{1}{2}n_{HCl} = 0,05(mol)\\ m_{dd\ sau\ pư} = 0,05.80 + 100 = 104(gam)\\ C\%_{CuCl_2} = \dfrac{0,05.135}{104}.100\% = 6,49\%\)
Bài 2L
a, PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
b, Ta có: 24nMg + 27nAl = 5,1 (g) (1)
\(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)
\(m_{HCl}=100.21,9\%=21,9\left(g\right)\Rightarrow n_{HCl}=\dfrac{21,9}{36,5}=0,6\left(mol\right)\)
Có: nHCl (pư) = 2nH2 = 0,5 (mol) < 0,6 → HCl dư.
⇒ nHCl (dư) = 0,6 - 0,5 = 0,1 (mol)
Theo PT: \(n_{H_2}=n_{Mg}+\dfrac{3}{2}n_{Al}=0,25\left(2\right)\)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{Mg}=0,1\left(mol\right)\\n_{Al}=0,1\left(mol\right)\end{matrix}\right.\)
Ta có: m dd sau pư = 5,1 + 100 - 0,25.2 = 104,6 (g)
Theo PT: \(\left\{{}\begin{matrix}n_{MgCl_2}=n_{Mg}=0,1\left(mol\right)\\n_{AlCl_3}=n_{Al}=0,1\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{HCl\left(dư\right)}=\dfrac{0,1.36,5}{104,6}.100\%\approx3,49\%\\C\%_{MgCl_2}=\dfrac{0,1.95}{104,6}.100\%\approx9,08\%\\C\%_{AlCl_3}=\dfrac{0,1.133,5}{104,6}.100\%\approx12,76\%\end{matrix}\right.\)
Bài 3:
Gọi: nH2 = a (mol)
BTNT H, có: nHCl = 2nH2 = 2a (mol)
Theo ĐLBT KL, có: mKL + mHCl = mA + mH2
⇒ 5 + 2a.36,5 = 5,71 + 2a ⇒ a = 0,01 (mol)
⇒ VH2 = 0,01.22,4 = 0,224 (l)
nCuO=4/80=0.05(mol)
nHCl=100x2.92/100x36.5=.08(mol)
==>nCuO dư, tính theo nHCl
CuO+2HCl-->CuCl2+H2O
0.04 0.08 0.04 (mol)
nCuO dư= 0.05-0.04=0.01(mol)
=>mCuO dư spu= 0.01x80=0.8(g)
mCuCl2=0.04x135=5.4(mol)