You add .800ml of saturated Ca(OH)2, u titrate with .02M of HCl and use 1.840 of the acid.How do i get the Ksp

Question

i know i need the molar solubility first to find the Ksp.But do i need to do ICF and ICE or what?I need help

Answer 1

Your question is not very well formulated but anyway.

You use the titration data to find the concentration of Ca(OH)2 in the saturated solution. This will correspond to the molar solubility of Ca(OH)2 so you can use it to find the Ksp.

In detail:
you have mole HCl= M1*V1= 0.02*1.84*10^-3 = 3.68*10^-5 (1)
mole Ca(OH)2= M2*V2= M2*0.8 (2)

Ca(OH)2 + 2HCl -> CaCl2 +2H2O
So the ratio is 1:2 =mole Ca(OH)2/mole HCl =>
2 *mole Ca(OH)2 = mole HCl Substitute from (1), (2) =>
2*M2*0.8= 3.68*10^-5 =>
M2=2.3 *10^-5 mole/L
But this is also the molar solubility, s (since the solution is saturated)

... .. .. ..Ca(OH)2 <=> Ca+2 +2OH-
Dissolve ..s
Produce .. .. .. .. .. .. .. . .s .. .. 2s

Ksp=[Ca+2][OH-]^2 = s*(2s)^2 = 4s^3 =4*(2.3 *10^-5)^3 =4.87*10^-14