\(n_{AgCl}=\dfrac{43,05}{143,5}=0,3\left(mol\right)\)
PTHH: 2R + 3Cl2 → 2RCl3
PTHH: RCl3 + 3AgNO3 → R(NO3)3 + 3AgCl
Mol: 0,1 0,3
\(\Rightarrow M_{RCl_3}=\dfrac{16,25}{0,1}=162,5\left(g/mol\right)\)
\(\Rightarrow M_R=162,5-3.35,5=56\left(g/mol\right)\)
⇒ R là kim loại sắt (Fe)