Question

6. Fluoride ion is often used in toothpastes, mouth rinses, and so on to help prevent tooth decay. It does so by making the hydroxyapatite of which our teeth is made even less soluble than it is naturally, by a factor of 100. The source of fluoride ion in these materials is often stannous fluoride, SnF2. It, too, is a slightly soluble salt, and has a Ksp = 1.8 x 10-9. How many moles of SnF2 will dissolve in 1.0 liter of water?______________________

Answer 1

the answer is 7.66 x 10 ^-4 moles will get dissolved in 1 litre of water .

The solubility equation of safe would be sih ? Sn 24 + 2f- IM 8 - EIM – 8 2 [sn²4] [F-7 Now, we know Kep = &, Kep = 1.8 X10 +9 = (8) (28)2 1.8810-9 = 483 = 7.66 X1D-4 M We know that unit M (molar) is also written as (mol 1L) do solubility of do Fr (s) = 7.66X10" mal IL which means, 7.66XL0" moles of bih is soluble in 1 litre of water.