Stoichiometry chemistry

Question

If 0.1141 moles of aluminum sulfide react with fluorine, to make aluminum fluoride and elemental sulfur (S), how many moles of fluorine are used up?

Answer 1

First you need the chemical formulas and balanced equation to determine the mole ratios.

Since Aluminum is group 3, sulfur group 6 and Fluorine group 7, we have the equation

Al₂S₃ + F --> AlF₃ + S (to determine the formulas, remember metals lose electrons to non metals).

Al₂S₃ + F --> 2AlF₃ + 3S (balance aluminum and sulfur)

Al₂S₃ + 6F --> 2AlF + 3S (balance fluorine to balance the equation)

From the the balanced equation, we see that every mole of aluminum sulfide needs six moles of fluorine to react. Thus 0.1141 moles of aluminum sulfide reacts with 6 times 0.1141 moles = 0.6846 moles of fluorine.