Lesson 4 Calculating Solubility 1 Calculate the solubility

Lesson 4 Calculating Solubility

1. Calculate the solubility @ 25 o. C for Ba. Cr. O 4 in units of g/L. ⇌ Ba. Cr. O 4(s) s from page 5 Ba 2+ s + Cr. O 42 s Ksp = [Ba 2+][Cr. O 42 -] Ksp = s 2 1. 2 x 10 -10 s = 1. 1 x 10 -5 M note that solubility units are M! 1. 1 x 10 -5 mole L x 253. 3 g 1 mole = 0. 0028 g/L

2. Calculate the solubility @ 25 o. C for Cu(IO 3)2 in units of g/L. ⇌ Cu(IO 3)2(s) Cu 2+ s 2. 584 x 10 -3 moles L + s 2 s Ksp = [Cu 2+][IO 3 -]2 Ksp = [s][2 s]2 Ksp = 4 s 3 6. 9 x 10 -8 = 4 s 3 s = 2. 6 x 10 -3 M x 413. 3 g 1 mole = 2 IO 3 - 1. 1 g/L note sig figs are 2 like the Ksp!

3. Calculate the molar solubility @ 25 o. C for Fe(OH)3. Calculate the mass required to prepare 2. 0 L of the above saturated solution. ⇌ Fe(OH)3 s 3 OH 3 s = [Fe 3+][OH-]3 Ksp = [s][3 s]3 = 27 s 4 = 9. 906 x 10 -11 M s x + Ksp 2. 6 x 10 -39 2. 0 L Fe 3+ s 9. 906 x 10 -11 mole L x 106. 8 g 1 mole = 2. 1 x 10 -8 g

The size of the Ksp is related to the solubility of the ionic compound. For salts that are comparable (AB versus AB), the larger the Ksp of the salt, the greater is its solubility. 4. Indicate the solid with the greatest solubility. Pb. SO 4 low Zn. S low Ag. Cl low Be. S high start on page 4 One of These Things is not like the Other

5. Indicate the solid with the least solubility. Pb. SO 4 low 1. 8 x 10 -8 Zn. S low 2. 0 x 10 -25 Ag. Cl low 1. 8 x 10 -10 Be. S high start on page 4 use page 5 if required The lowest ksp is the lowest solubility

6. A solution of Ag. NO 3 is slowly added to a mixture containing 0. 10 M I-, Cl-, Br-, and IO 3 -. The precipitate, which forms first, is Ag. I low 8. 5 x 10 -17 Ag. Cl low 1. 8 x 10 -10 Ag. Br low 5. 4 x 10 -13 Ag. IO 3 low 3. 2 x 10 -8 lowest ksp – 1 st ppt to form

7. A few drops of Ag. NO 3 is added to four beakers containing 0. 10 M I-, Cl-, Br, and IO 3 -. A precipitate forms in three of the solutions. The solution that does not form a precipitate is? Ag. I low 8. 5 x 10 -17 Ag. Cl low 1. 8 x 10 -10 Ag. Br low 5. 4 x 10 -13 Ag. IO 3 low 3. 2 x 10 -8 highest ksp – last ppt to form Sodium acetate sculptures