\(m_{Fe}=32.70\%=22,4\left(g\right)\\ n_{Fe}=\dfrac{22,4}{56}=0,4\left(mol\right)\\ m_{Mg}=32-22,4=9,6\left(g\right)\\ n_{Mg}=\dfrac{9,6}{24}=0,4\left(mol\right)\\ 3Fe+2O_2\rightarrow\left(t^o\right)Fe_3O_4\\ 2Mg+O_2\rightarrow\left(t^o\right)2MgO\\ n_{O_2\left(tổng\right)}=\dfrac{2}{3}.n_{Fe}+\dfrac{1}{2}.n_{Mg}=\dfrac{2}{3}.0,4+\dfrac{1}{2}.0,4=\dfrac{7}{15}\left(mol\right)\\ V_{O_2\left(đktc\right)}=\dfrac{7}{15}.22,4=\dfrac{784}{75}\left(l\right)\\ V_{kk\left(đktc\right)}=\dfrac{784}{75}.\dfrac{100}{20}=\dfrac{784}{15}\left(l\right)\\ b,n_{Fe_3O_4}=\dfrac{1}{3}.0,4=\dfrac{2}{15}\left(mol\right)\\ n_{MgO}=n_{Mg}=0,4\left(mol\right)\\ m_{rắn}=m_{Fe_3O_4}+m_{MgO}=\dfrac{232.2}{15}+0,4.40=\dfrac{704}{15}\left(g\right)\)
\(a,m_{Fe}=\%Fe.m_{hh}=70\%.32=22,4\left(g\right)\)
\(m_{Mg}=m_{hh}-m_{Fe}=32-22,4=9,6\left(g\right)\)
\(n_{Fe}=\dfrac{m}{M}=\dfrac{22,4}{56}=0,4\left(mol\right)\\ n_{Mg}=\dfrac{m}{M}=0,4\left(mol\right)\)
\(PTHH:3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\left(1\right)\)
\(PTHH:2Mg+O_2\underrightarrow{t^o}2MgO\left(2\right)\)
\(Theo.PTHH\left(1\right):n_{O_2\left(Fe\right)}=\dfrac{2}{3}n_{Fe}=\dfrac{2}{3}.0,4=\dfrac{4}{15}\left(mol\right)\)
\(Theo.PTHH\left(2\right):n_{O_2\left(Mg\right)}=2n_{Mg}=2.0,4=0,8\left(mol\right)\)
\(\Rightarrow n_{O_2\left(tổng\right)}=n_{O_2\left(Fe\right)}+n_{O_2\left(Mg\right)}=\dfrac{4}{15}+0,8=\dfrac{16}{15}\left(mol\right)\)
\(\Rightarrow V_{O_2\left(đktc\right)}=n.22,4=\dfrac{16}{15}.22,4=\dfrac{1792}{75}\left(l\right)\)
\(\Rightarrow V_{kk}=V_{O_2}.5=\dfrac{1792}{75}.5=\dfrac{1792}{15}\left(l\right)\)
