Question

Calculate the concentration of flouride ions in a saturated barium fluoride solution (given ksp for Barium Fluoride = 1.7x10^-6). Show your work for your answer.

a) 7.6x10^-3

b)1.5x10^-2

c) 3.4x10^-5

d) 1.7x10^-6

e) 3.4x10^-6

Answer 1

Answer is (a)

BaF2

Molar mass of BaF2 =175.34 g/mol

BaF2(aq) = Ba²⁺ (aq) + 2F^- (aq)

                   x                  2x     at equillibrium

Ksp = [Ba²⁺][F^-]²

Let us consider the solubility of fluoride ions = x M, then

Then, Ksp = x *(2x)², or 4x³ = (1.7x10^-6)

x³ =(1.7/4)x10^-6

x = 7.6x10^-3 M

So, the solubility of BaF2 = 7.6x10^-3 M