nhấn vào đây

PTHH:

2Mg + O2 =(nhiệt)=> 2MgO (1)

4Al + 3O2 =(nhiệt=> 2Al2O3 (2)

Ta có: n_Al = \(\dfrac{2,7}{27}=0,1\left(mol\right)\)

\(\Sigma n_{O_2}=\dfrac{33,6}{22,4}=1,5\left(mol\right)\)

+) n_O2 (2) = \(\dfrac{0,1.3}{4}=0,075\left(mol\right)\)

=> nO2(1) = 1,5 - 0,075 = 1,425 (mol)

=> nMg = 1,425 x 2 = 2,85 (mol)

=> mMg = 2,85 x 24 = 68,4 (gam)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{68,4}{68,4+2,7}.100\%=96,2\%\\\%m_{Al}=100\%-96,2\%=3,8\%\end{matrix}\right.\)

H=100%(cái này quan trọng này)

\(n_{Al}=\dfrac{2,7}{27}=0,1\left(mol\right)\\ n_{O_2}=\dfrac{33,6}{22,4}=1,5\left(mol\right)\\ 2Al+3O_2\underrightarrow{t^o}2Al_2O_3\)

n(bd) 0,1 1,5

n(spu) 0 1,35\

\(2Mg+O_2\underrightarrow{t^o}2MgO\)

2,7 1,35

\(m_{hh}=2,7+24.2,7=67,5\left(g\right)\\ \%m_{Al}=\dfrac{2,7\cdot100\%}{67,5}=4\left(\%\right)\\ \Rightarrow\%m_{Mg}=100\%-4\%=96\%\)

mk thấy hơi to bạn kiểm tra lại đi

PT: \(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)

\(2Mg+O_2\underrightarrow{t^o}2MgO\)

Ta có: \(n_{Al}=\dfrac{2,7}{27}=0,1\left(mol\right)\)

\(n_{O_2}=\dfrac{3,7185}{24,79}=0,15\left(mol\right)\)

Theo PT: \(n_{O_2}=\dfrac{3}{4}n_{Al}+\dfrac{1}{2}n_{Mg}\) \(\Rightarrow n_{Mg}=0,15\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{2,7}{2,7+0,15.24}.100\%\approx42,86\%\\\%m_{Mg}\approx57,14\%\end{matrix}\right.\)

PTHH: \(4Al+3O_2\underrightarrow{t^o}2Al_2O_3\)  (1)

            \(2Mg+O_2\underrightarrow{t^o}2MgO\)  (2)

Ta có: \(\left\{{}\begin{matrix}n_{O_2\left(1\right)}=\dfrac{3}{4}n_{Al}=\dfrac{3}{4}\cdot\dfrac{13,5}{27}=0,375\left(mol\right)\\n_{O_2\left(1\right)}+n_{O_2\left(2\right)}=\dfrac{16,8}{22,4}=0,75\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow n_{O_2\left(2\right)}=0,375\left(mol\right)\) \(\Rightarrow n_{Mg}=0,75\left(mol\right)\)

\(\Rightarrow\%m_{Mg}=\dfrac{0,75\cdot24}{0,75\cdot24+13,5}\cdot100\%\approx57,14\%\)