J.R. S. answered 04/17/19
Ph.D. University Professor with 10+ years Tutoring Experience
2Al(s) + 3F2(g) ==> 2AlF3(s)
moles of Al used = 8.8x1023 atoms x 1 mole/6.02x1023 atoms = 1.46 moles Al
moles of F2(g) required = 1.46 moles Al x 3 moles F2/2 mole Al = 2.19 moles F2 needed
The volume (liters) of F2 required will depend on the temperature and pressure of the system. If we assume STP (atm and 273K), and assume F2 behaves as an idea gas, then ...
2.19 moles F2(g) x 22.4 L/mole = 49 liters F2 gas required (to 2 signifiant figures)