Answer to Question #183917 in General Chemistry for Sübahan Abdullayev

Question

Fluoride ion is added to drinking water to prevent tooth decay. What is the mass (g) of sodium

fluoride in a liter of water that contains 1.193 * 10 19 formula units of the compound? Include a

road map that shows how you planned the solution.

Answer 1

NaF₂+H₂O → 2HF + NaOH

1 mole = 6.022 × 10²³ formula units

= 1.193 × 10¹⁹/6.022 × 10²³

= 1.98 × 10^-5

= 0.0000198 moles

From the equation, 1mole NaF2 = 1mole H2O

= 0.0000198 mole of H₂O

Molar Mass of H₂O = 18.01528

= 0.0000198 × 18.01528

= 0.0003567g of NaF