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\(4K+O_2\rightarrow\left(t^o\right)2K_2O\\ 1.n_K=\dfrac{5,85}{39}=0,15\left(mol\right)\\ \Rightarrow n_{K_2O}=\dfrac{0,15}{2}=0,075\left(mol\right)\\ m_{K_2O}=94.0,075=7,05\left(g\right)\\ 2,n_K=\dfrac{9,36}{39}=0,24\left(mol\right)\\ n_{O_2}=\dfrac{0,24}{4}=0,06\left(mol\right)\\ V_{O_2\left(đkc\right)}=0,06.24,79=1,4874\left(l\right)\)
\(Câu.2:\\ 2KClO_3\rightarrow\left(t^o\right)2KCl+3O_2\\ n_{KClO_3}=\dfrac{14,7}{122,5}=0,12\left(mol\right)\\ n_{KCl}=n_{KClO_3}=0,12\left(mol\right);n_{O_2}=\dfrac{3}{2}.0,12=0,18\left(mol\right)\\ V_{O_2\left(đkc\right)}=0,18.24,79=4,4622\left(l\right)\\ m_{KCl}=74,5.0,12=8,94\left(g\right)\)
Câu 3:
\(n_{Al}=\dfrac{8,1}{27}=0,3\left(mol\right)\\ PTHH:2Al+6HCl\rightarrow2AlCl_3+3H_2\\ n_{H_2}=\dfrac{3}{2}.n_{Al}=\dfrac{3}{2}.0,3=0,45\left(mol\right)\\ 1,V_{H_2\left(đkc\right)}=24,79.0,45=11,1555\left(l\right)\\ 2,n_{HCl}=\dfrac{6}{2}.0,3=0,9\left(mol\right)\\ V_{ddHCl}=\dfrac{0,9}{1,5}=0,6\left(l\right)\\ 3,n_{AlCl_3}=n_{Al}=0,3\left(mol\right)\\ V_{ddsau}=V_{ddHCl}=0,6\left(l\right)\\ C_{MddAlCl_3}=\dfrac{0,3}{0,6}=0,5\left(M\right)\)
2Mg + O2 --to--> 2MgO
Theo ĐLBTKL: mMg + mO2 = mMgO
=> mO2 = 4-2,4 = 1,6(g)
\(2Mg+O_2\underrightarrow{t^o}2MgO\\ m_{Mg}+m_{O_2}=m_{MgO}\\ \Rightarrow m_{O_2}=m_{MgO}-m_{Mg}=4-2,4=1,6\left(g\right)\)
Áp dụng định luật BTKL:
\(a,m_{Mg}+m_{O_2}=m_{MgO}\\ b,m_{O_2}=m_{MgO}-m_{Mg}=50-42=8\left(g\right)\)
\(n_{Al}=\dfrac{0,54}{27}=0,02\left(mol\right)\)
Pt : \(4Al+3O_2\xrightarrow[]{t^o}2Al_2O_3\)
0,02-->0,015-->0,01
a) \(m_{Al2O3}=0,01.102=1,02\left(g\right)\)
b) \(V_{O2\left(dktc\right)}=0,015.24,79=0,37185\left(l\right)\)
sửa lại \(V_{\left(dktc\right)}-->V_{\left(dkc\right)}\)
\(PTHH:4K+O_2\rightarrow2K_2O\\ m_K+m_{O_2}=m_{K_2O}\\ \Rightarrow m_{O_2}=m_{K_2O}-m_K=35-20=15\left(g\right)\)