Em chưa học ion thì em cứ viết hết PTHH cho anh nha!
\(2Mg+O_2\rightarrow\left(t^o\right)2MgO\left(1\right)\\ 4Al+3O_2\rightarrow\left(t^o\right)2Al_2O_3\left(2\right)\\ 2Zn+O_2\rightarrow\left(t^o\right)2ZnO\left(3\right)\\ MgO+2HCl\rightarrow MgCl_2+H_2O\left(4\right)\\ Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\left(5\right)\\ ZnO+2HCl\rightarrow ZnCl_2+H_2O\left(6\right)\\ Từ.các.PTHH\left(4\right),\left(5\right),\left(6\right):n_{O\left(trong.oxit\right)}=\dfrac{n_{H\left(trong.HCl\right)}}{2}=\dfrac{n_{HCl}}{2}=\dfrac{0,2.3}{2}=0,3\left(mol\right)\\ m=m_{kl}=m_{oxit}-m_{O\left(trong.oxit\right)}=20-0,3.16=15,2\left(g\right)\)
\(n_{H^+}=n_{HCl}=0,2.3=0,6\left(mol\right)\\ 2H^++O^{2-}\rightarrow H_2O\\ \Rightarrow n_{O^{2-}}=\dfrac{0,6}{2}=0,3\left(mol\right)\\ m=m_{hh\left(Mg,Al,Zn\right)}=m_{hh.oxit}-m_{O^{2-}}=20.0,3.16=15,2\left(g\right)\)
