\(n_{CaS}=0,015625\left(mol\right)\)
\(CaS+2HCl-->CaCl_2+H_2S\)
theo PTHH
\(n_{HCl}=2n_{CaS}=2.0,015625=0,03125\left(mol\right)\)
\(FeO+2HCl-->FeCl_2+H_2O\)
\(2n_{HCl}=n_{FeO}=\dfrac{0,03125}{2}=0,015625\left(mol\right)\)
\(m_{FeO}=0,015625.72=1,125\left(g\right)\)