the balanced equation for the reaction is as follows
2 Al + 3 Cl₂ ---> 2 AlCl₃
molar ratio of Cl₂ to AlCl₃ is 3:2
mass of Cl₂ reacted is - 11.5 g
number of moles of Cl₂ reacted - 11.5 g / 71 g/mol = 0.162 mol
when 3 mol of Cl₂ reacts - 2 mol of AlCl₃ is formed
therefore when 0.162 mol of Cl₂ reacts - 2/3 x 0.162 mol = 0.108 mol of AlCl₃ is formed
the molar mass of AlCl₃ is 133 g/mol
mass of AlCl₃ formed is - 0.108 mol x 133 g/mol = 14.4 g
mass of AlCl₃ formed is 14.4 g