equilibrium

[william]

The Ksp for CaF2 is 3.9 x 10-11 at 25oC. What is the (a) molar solubility of CaF2 in water? (b) What is the solubility in grams per liter?

[TheMasterMind]

The Ksp for CaF2 is 3.9 x 10-11 at 25oC. What is the (a) molar solubility of CaF2 in water? (b) What is the solubility in grams per liter?

a/

you must set up an equilibrium table. let x=[Ca^2+]

if i got the table and designation of variables correct the result is:

Ksp=[Ca^2+][F^-]^2=(x)(2x)^2=4x^3=3.9x10^-11

thus a/=x=(3.9x10^-11/4)^1/3=2.1x10^-4M

b/

convert moles per liter to grams per liter (of CaF2)

[Russ]

Following on for b)

to convert moles/litre to grams/litre just multiply the number of moles by the formula mass of CaF2

[TheMasterMind]

for a check for b/ = 1.6x10^-2 g/L solution