University:
Bradley University
Course:
CHM 116 | General Chemistry II
Academic year:

2023
Views:

146

Pages:

3
Author:

Reynaldo Wong

PAL – Week 7 (Mon/Tu) #10 Solubility and precipitation (sec. 16.5-16.6) Name: Part A: Understanding Ksp Conceptually True or False 2+ 2 2- The solubility product constant for the salt CoS is: [Co ] [S ] CuS (Ksp = 8 x 10 -37 ) is more soluble than MnS (Ksp = 7 x 10 -16 ) Ksp, is the equilibrium constant for a solid substance dissolving in an aqueous solution. The more soluble the substance, the smaller the solubility product constant (Ksp). We cannot compare the solubility constants of two compounds when the ratio of ions is not the same. (e.g. FeCO3 (Ksp = 3.1 x 10 -11 ) to Fe(OH)2 (Ksp = 4.9 x 10 -17 ). The solubility of a salt in the presence of a common ion has a lower solubility. The solubility of an ionic compound with a basic anion increases in acid. Part B: Ksp and Molar solubility -8 1) The Ksp of lead(II) sulfate is 1.6 x 10 . a) Write the expression of the solubility product constant (Ksp) for lead sulfate. b) What is the molar solubility of lead(II) sulfate in pure water? c) Would you expect the molar solubility of lead(II) sulfate to be lower or higher in a solution that 2has [SO4 ] = 0.25 M. Calculate the solubility and compare. 1 Part C: The solubility of salts in acidic and basic solutions 2) The Ksp of lead(II) hydroxide is 4.2 x 10 -15 . a) Write the expression of the solubility product constant (Ksp) for lead hydroxide. b) What is the molar solubility of lead(II) hydroxide in pure water? c) Would you expect the solubility to be higher or lower in an acidic solution? How about a basic solution? d) What is the solubility of lead(II) hydroxide in a pH = 4.00 buffer? (hint: although we are + referring to an acid solution, remember that OH and H3O are related to each other (i.e.[OH + ][H3O ] = Kw and pH+pOH = 14) so approach this problem by calculating pOH and [OH ] and use [OH ] in ICE table.) e) What is the solubility of lead hydroxide in a pH = 11.00 buffer? 2 Part D: Comparing the solubility of salts 3) Based on the Ksp values provided below for six lead salts. Can you predict which is most soluble and which is least? Would you have to calculate the solubility of each? Salt Pb(OH)2 PbF2 PbI2 PbC2O4 PbSO4 PbCrO4 Ksp -15 4.2 x 10 -8 4.0 x 10 -8 1.4 x 10 -11 3.0 x 10 -8 1.6 x 10 -14 1.7 x 10 3