What mass of Al2(SO4)3 results from mixing 12.93 g of AlCl3 with 10.34 g of (NH4)2SO3 as shown with a 54.2% yield?

Mass of Al₂(SO₄)₃ : 4.822 g

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.  

Reaction

2AlCl₃ + 3(NH₄)₂SO₄⇒Al₂(SO₄)₃+ 6NH₄Cl

MW AlCl₃ :133,34 g/mol

MW (NH₄)₂SO₄ : 132,14 g/mol

MW Al₂(SO₄)₃ : 342,15 g/mol

mol  AlCl₃

mol (NH₄)₂SO₄

Limitng reactants (ratio mol : coefficient = the smaller)

AlCl₃ : (NH₄)₂SO₄ =

(NH₄)₂SO₄ ⇒ limiting reactants

So mol Al₂(SO₄)₃ from (NH₄)₂SO₄

mass Al₂(SO₄)₃

with 54.2% yield, the mass of Al₂(SO₄)₃