6 HF+SiO2–>H2SiF6+ 2 H2O

6 HF+SiO2–>H2SiF6+ 2 H2O

If 3.00 moles of HF reacts with SiO2, and 1.50 moles of SiO2 were initially present, what is the fractional excess of SiO2?

What is the percent excess of SiO2?