Gọi KL là M
a) 2M+ 6HCl----->2MCl3+3H2
n\(_{HCl}=\frac{21,9}{36,5}=0,6\left(mol\right)\)
Theo pthh
n\(_M=\frac{1}{3}n_{HCl}=0,2\left(mol\right)\)
M\(_M=\frac{5,4}{0,2}=27\left(g\right)\)
=> M là Al
b) Theo pthh
n\(_{AlC_{ }l3}=\frac{1}{3}n_{HCl}=0,2\left(mol\right)\)
m\(_{AlCl3}=0,2.133,5=26,7\left(g\right)\)
c) Tự làm nhé