Chemistry Help Please!

Question

If .2784 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

Let's start with a balanced equation.

2Al₂S₃ + 6F₂ = 4AlF₃ + 6S

The equation tells us that we need six moles of F₂ for every two moles of Al₂S₃. That's a ratio of 6:2 or 3:1.

If we assume we have plenty of F₂ and also have 0.2784 moles of Al₂S₃, then we will consume three times that amount of F₂, which would be 0.8352 moles of F₂.