Molar mass :
Li₂S = 45.947 g/mol
AlCl₃ = 133.34 g/mol
3 Li₂S + 2 AlCl₃ = 6 LiCl + Al₂S₃
3 * 45.947 g Li₂S ----------> 2 * 133.34 g AlCl₃
1.084 g Li₂S ----------------> ?
Mass Li₂S = 1.084 * 2 * 133.34 / 3 * 45.947
Mass Li₂S = 289.08112 / 137.841
Mass Li₂S = 2.0972 g
hope this helps!
