2. Calculate the mass of Naf used if you have 508 mL of a 2.75-molar NaF solution.

58.7g

Explanation:

Given parameters:

Volume of solution of NaF = 508mL   = 0.508dm³

Concentration  = 2.75M

Unknown:

Mass of NaF used  = ?

Solution:

Concentration in this regard is molarity. Molarity of a solution is the amount of solute dissolved in a solution. Here the number of moles of solute in a given volume of solution gives molarity.

   Molarity  =

Using this expression, let us find the number of moles of NaF;

              Number of moles of NaF  = molarity x volume

                                                         = 2.75 x 0.508

                                                          = 1.397moles

Now;

         Mass of NaF  = number of moles x molar mass

            Molar mass of NaF  = 23 + 19  = 42g/mol

        Mass of NaF  = 1.397  x 42  = 58.7g

the answer is na (sodium)