\(n_{Mg}=\dfrac{3,12}{24}=0,13\left(mol\right)\)
\(n_{H_2}=\dfrac{2,2311}{25,79}=0,09\left(mol\right)\)
PTHH :
\(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)
0,09 0,18 0,09 0,09
\(\dfrac{0,13}{1}>\dfrac{0,09}{1}\) --> Mg dư
\(m_{MgCl_2}=0,09.95=8,55\left(g\right)\)
PTHH :
\(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)
0,13 0,26 0,13 0,13
\(V_{H_2\left(lt\right)}=0,13.24,79=3,2227\left(l\right)\)
\(H=\dfrac{2,2311}{3,2227}.100\%\approx69,23\%\)