How many moles of sulfur is needed to react with 56.4 grams of aluminum?

Question

I don't know how to start

Answer 1

1) We need to write the reaction down

Aluminium + Sulfur ---> Aluminum sulfide

Al + S ---> Al2S3

2) We need to balance the equation

2Al + 3S ---> Al2S3

3) Use dimensional analysis to check for units, use the periodic table to get the molar mass and used the balanced equation for our fractions:

56.4 g Al x (1mol Al) / (25.982 g Al) x

(3 mol S) / (2 mol Al) = 3.2561 mol S