The molarity of NaF(sodium fluoride) in a brand of toothpaste was found to be3.16*10-4M. How do I determine the %w/w (percentweight by weight) of fluoride ion in the toothpaste from themolarity? The molecular weight of NaF is 41.99, and thedensity of the toothpaste is 0.9681g/cm3.

Alright, I figured out thegrams of NaF to be:

grams of NaF = 3.16x 10-4 moles of NaF x 41.9 g/mol = .013 g of NaF in aLiter

Then I figured out themass of a liter of toothpaste using density = mass/volume:
1000 cm3 x .9681 g/cm3 = 968.1g

So the %w/w should bepart/whole x 100:
0.013g/968.1 x 100 = 0.0013%

This is off by about afactor of 100 when compared to the reported w/w on the label forthe toothpaste (0.14%). Can someone point out where I'm goingwrong?