Sodium fluoride (NaF) is added to drinking water in some municipalities to protect teeth against cavities. The idea is to convert hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂, into more stable fluorapatite, Ca₁₀(PO₄)₆F₂. The molar mass of hydroxyapatite is 502 g/mol. What is the molarity of a 10.0 mg/L sodium fluoride solution?

Question

Quizplus · Accepted Answer

The molarity of a solution is defined as the number of moles of solute per liter of solution. To calculate the molarity of a sodium fluoride solution, we need to know the number of moles of sodium fluoride in 1 liter of solution.To do this, we can use the following formula:Molarity = (Mass of solute in grams) / (Molar mass of solute in grams/mol) x (Volume of solution in liters)In this case, we have 10.0 mg of sodium fluoride in 1 liter of solution. The molar mass of sodium fluoride is 41.99 g/mol.So, the molarity of the solution is:Molarity = (10.0 mg / 1000) / (41.99 g/mol) x (1 L) = 2.38 * 10^-4 MTherefore, the correct answer is A.

Sodium Fluoride (NaF) Is Added to Drinking Water in Some