\(n_{H2}=\frac{6,72}{22,4}=0,3\left(mol\right)\)
Phản ứng xảy ra:
\(2M+6HCl\rightarrow2MCl_3+3H_2\left(1\right)\)
\(M_2O_3+6HCl\rightarrow2MCl_3+3H_2O\left(2\right)\)
Theo PTHH 1:
\(\Rightarrow n_M=\frac{2}{3}.0,3=0,2\left(mol\right)\)
Vì \(\frac{n_{M2O3}}{n_M}=\frac{3}{4}\)
\(\Rightarrow n_{M2O3}=\frac{3}{4}.0,2=0,15\left(mol\right)\)
\(\Rightarrow0,2.M+0,15.\left(2M+16.3\right)=20,7\)
\(\Rightarrow M=27\left(Al\right)\)
Vậy M là Nhôm (Al)