Answer:
36 moles of HF
Explanation:
Let's consider the following reaction
4 HF + SiO₂ → SiF₄ + 2 H₂O
The molar ratio of HF to SiO₂ is 4 mol HF:1 mol SiO₂. We can use a conversion fraction to find the moles of HF that will react completely with 9.0 moles of SiO₂.
9.0 mol SiO₂ × (4 mol HF / 1 mol SiO₂) = 36 mol HF
36 moles of HF will react completely with 9.0 moles of SiO₂.
