Grams of Calcium Fluoride

Question

1. Calcium fluoride (CaF2) is often used as the source of fluoride ions (F–) in drinking water to prevent tooth decay. The question is: How many grams of calcium fluoride must be added to a 6.00x108 gallon (gal) storage reservoir to have a concentration of 1.00 mg fluoride ion per liter of water, (1.00 mg F–/L)?
2. Complete the units map on how this problem is most easily solved.
3. gal → liter →

Numerically solve this problem.

Answer 1

I solved this using dimensional analysis:

6.00 x 10⁸ gal x ( 3.79 Liters/ 1 gal) x (1 mg Fluorine/ 1 L) x (1 g Fluorine/ 1000 mg) x (1 mole Fluorine/ 19.0 g) x (1 mol CaF₂ / 2 moles F) x (78.08 g/ 1 mol F) = 4.67 x 10⁶ grams.

Therefore, 4.67 x 10⁶ grams of CaF₂ will need to be added.