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nH2 = \(\frac{1,68}{22,4}\) = 0,075 (mol)
Mg + 2HCl \(\rightarrow\) MgCl2 + H2\(\uparrow\) (1)
0,075 <--------0,075 <--0,075 (mol)
MgO + 2HCl \(\rightarrow\) MgCl2 + H2O (2)
%mMg= \(\frac{0,075.24}{5,8}\) . 100% = 31,03 %
%m MgO = 68,97%
nMgO = \(\frac{5,8-0,075.24}{40}\) = 0,1 (mol)
Theo pt(2) nMgCl2 = nMgO= 0,1 (mol)
mdd sau pư = 5,8 + 194,35 - 0,075.2 = 200 (g)
C%(MgCl2) = \(\frac{95\left(0,075+0,1\right)}{200}\) . 100% = 8,3125%
PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\) (1)
\(MgO+2HCl\rightarrow MgCl_2+H_2O\) (2)
a) Ta có: \(n_{H_2}=\dfrac{22,4}{22,4}=1\left(mol\right)=n_{Mg}\) \(\Rightarrow m_{Mg}=1\cdot24=24\left(g\right)\)
\(\Rightarrow\%m_{Mg}=\dfrac{24}{32}\cdot100\%=75\%\) \(\Rightarrow\%m_{MgO}=25\%\)
b) Theo 2 PTHH: \(\left\{{}\begin{matrix}n_{HCl\left(1\right)}=2n_{Mg}=2mol\\n_{HCl\left(2\right)}=2n_{MgO}=2\cdot\dfrac{32-24}{40}=0,4mol\end{matrix}\right.\)
\(\Rightarrow\Sigma n_{HCl}=2,4mol\) \(\Rightarrow m_{ddHCl}=\dfrac{2,4\cdot36,5}{7,3\%}=1200\left(g\right)\)
c) Theo PTHH: \(\Sigma n_{MgCl_2}=\dfrac{1}{2}\Sigma n_{HCl}=1,2mol\)
\(\Rightarrow\Sigma m_{MgCl_2}=1,2\cdot95=114\left(g\right)\)
Mặt khác: \(m_{H_2}=1\cdot2=2\left(g\right)\)
\(\Rightarrow m_{dd}=m_{hh}+m_{ddHCl}-m_{H_2}=1230\left(g\right)\)
\(\Rightarrow C\%_{MgCl_2}=\dfrac{114}{1230}\cdot100\%\approx9,27\%\)
\(Fe+H_2SO_4\rightarrow FeSO_4+H_2\\ FeO+H_2SO_4\rightarrow FeSO_4+H_2O\)
nH2=4,48/22,4=0,2(mol)
=>nFe=0,2(mol)=>mFe=0,2.56=11,2(g)
=>mFeO=18,4-11,2=7,2(g)
b)nH2SO4=nH2=0,2(mol)
=>mH2SO4 7%=0,2.98=19,6(g)
=>mH2SO4 =19,6:7%=280(g)
c)mFeSO4=0,2.152=30,4(g)
mdd sau pư=18,4+280-0,2.2=298(g)
=>C%FeSO4=\(\frac{30,4}{298}.100\%\)=10,2%
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(MgO+2HCl\rightarrow MgCl_2+H_2O\)
Gọi a,b lần lượt là sm của Mg, MgO
Ta có: \(\left\{{}\begin{matrix}24a+40b=6\\a=0,1\end{matrix}\right.\Rightarrow b=0,09\)
\(\Rightarrow\%m_{MgO}=\dfrac{0,09.40}{6}.100=60\%\)
PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\) (1)
\(MgO+2HCl\rightarrow MgCl_2+H_2O\) (2)
a) Ta có: \(n_{H_2}=\frac{2,24}{22,4}=0,1\left(mol\right)\) \(\Rightarrow n_{Mg}=0,1mol\)
\(\Rightarrow m_{Mg}=0,1\cdot24=2,4\left(g\right)\) \(\Rightarrow m_{MgO}=4\left(g\right)\)
b) Ta có: \(\left\{{}\begin{matrix}n_{HCl\left(1\right)}=2n_{Mg}=0,2mol\\n_{HCl\left(2\right)}=2n_{MgO}=2\cdot\frac{4}{40}=0,2mol_{ }\end{matrix}\right.\)
\(\Rightarrow n_{HCl}=0,4mol\) \(\Rightarrow V_{ddHCl}=\frac{0,4}{1}=0,4\left(l\right)=400\left(ml\right)\)
c) Ta có: \(\left\{{}\begin{matrix}n_{MgCl_2\left(1\right)}=n_{Mg}=0,1mol\\n_{MgCl_2\left(2\right)}=n_{MgO}=0,1mol\end{matrix}\right.\)
\(\Rightarrow m_{muối}=m_{MgCl_2\left(1\right)}+m_{MgCl_2\left(2\right)}=0,1\cdot40+0,1\cdot40=8\left(g\right)\)