1. Lesson 4 Calculating Solubility

2. 1.Calculate the solubility @ 25 o C for BaCrO 4 in units of g/L. BaCrO 4(s) ⇌ Ba 2+ +CrO 4 2- ssssss Ksp=[Ba 2+ ][CrO 4 2- ] Ksp=s 2 s=1.1 x 10 -5 M note that solubility units are M! 1.2 x 10 -10 =s 2 from page 5 1.1 x 10 -5 molex 253.3 g = 0.0028 g/L L 1 mole

3. 2.Calculate the solubility @ 25 o C for Cu(IO 3 ) 2 in units of g/L. s=2.6 x 10 -3 M 6.9 x 10 -8 =4s 3 Ksp=4s 3 Ksp=[s][2s] 2 Ksp=[Cu 2+ ][IO 3 - ] 2 s s2s Cu(IO 3 ) 2(s) ⇌ Cu 2+ +2IO 3 - =1.1 g/L x 413.3 g 1 mole 2.584 x 10 -3 moles L note sig figs are 2 like the Ksp!

4. 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 ⇌ Fe 3+ +3OH - ss3s Ksp=[Fe 3+ ][OH - ] 3 Ksp=[s][3s] 3 2.6 x 10 -39 =27s 4 s=9.906 x 10 -11 M 2.0 Lx 9.906 x 10 -11 mole x 106.8 g = 2.1 x 10 -8 g 1 moleL

5. 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. PbSO 4 ZnS AgCl BeS One of These Things is not like the Other low high start on page 4 low

6. 5.Indicate the solid with the least solubility. PbSO 4 low ZnSlow AgCllow BeS high 1.8 x 10 -10 2.0 x 10 -25 use page 5 if required 1.8 x 10 -8 start on page 4 The lowest ksp is the lowest solubility

7. 6.A solution of AgNO 3 is slowly added to a mixture containing 0.10 M I -, Cl -, Br -, and IO 3 -. The precipitate, which forms first, is AgI AgCl AgBr AgIO 3 low 8.5 x 10 -17 1.8 x 10 -10 5.4 x 10 -13 3.2 x 10 -8 lowest ksp – 1 st ppt to form

8. 7.A few drops of AgNO 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? AgI AgCl AgBr AgIO 3 low Sodium acetate sculptures 8.5 x 10 -17 1.8 x 10 -10 5.4 x 10 -13 3.2 x 10 -8 highest ksp – last ppt to form