Chapter 18 solubility and complex ion equilibria
This presentation is the property of its rightful owner.
Sponsored Links
1 / 9

Chapter 18: Solubility and Complex-Ion Equilibria PowerPoint PPT Presentation


  • 54 Views
  • Uploaded on
  • Presentation posted in: General

Chapter 18: Solubility and Complex-Ion Equilibria. Chemistry 1062: Principles of Chemistry II Andy Aspaas, Instructor. Solubility product constant. Excess of a slightly-soluble ionic compound is mixed with water An equilibrium occurs between the solid ionic compound and the dissociated ions

Download Presentation

Chapter 18: Solubility and Complex-Ion Equilibria

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chapter 18 solubility and complex ion equilibria

Chapter 18: Solubility andComplex-Ion Equilibria

Chemistry 1062: Principles of Chemistry II

Andy Aspaas, Instructor


Solubility product constant

Solubility product constant

  • Excess of a slightly-soluble ionic compound is mixed with water

  • An equilibrium occurs between the solid ionic compound and the dissociated ions

    CaC2O4(s) = Ca2+(aq) + C2O42-(aq)

  • Equilibrium constant for this process is called solubility product constant, Ksp

    Ksp = [Ca2+][C2O42-]

    (since only aqueous components are included in an equilibrium expression)

  • In the Kspequation, raise an ion’s concentration to the power of its stoichiometric number in the chemical equation


Solubility and k sp

Solubility and Ksp

  • The solubility of silver chloride is 1.9 x 10-3 g/L. What is Ksp?

    • First convert the solubility to molar solubility (mol/L)

    • Use an ICE table to find equilibrium molar concentrations of the ions (using 0 as initial) – ignore the solid

    • Substitute concentrations into a Ksp expression


Solubility and k sp1

Solubility and Ksp

  • Remember to account for the correct number of ions forming in their molar concentrations

  • The solubility of Pb3(AsO4)2 is 3.0 x 10-5 g/L. What is Ksp?

  • Since a single formula unit of lead arsenate forms 3 Pb2+ ions when dissolved, be sure to multiply 3 by the molar concentration in the C row of the ICE table


Calculating solubility

Calculating solubility

  • What is the solubility of calcium phosphate, in g/L? Ksp = 1 x 10-26

  • Create an equilibrium expression with correct stoichiometry

  • In an ICE table, use x as the unknown change of molar concentrations, multiplying stoichiometric numbers by x

  • Solve for x in Ksp expression

  • Convert mol/L to g/L


Solubility and the common ion effect

Solubility and the common-ion effect

  • Addition of extra ion to a solubility equilibrium solution will shift the equilibrium according to Le Chatelier’s principle

  • Ex. Adding additional Ca2+ to this equilibrium:

    CaC2O4(s) = Ca2+(aq) + C2O42+(aq)

  • This will cause the equilibrium to shift to the left, and the solid will become less soluble


Common ion effect calculation

Common-ion effect calculation

  • Compare the molar solubilities of BaF2 in pure water and in 0.15 M NaF. Ksp = 1.0 k 10-6.

  • Set up the water solution as before and solve for molar solubility (x)

  • In the NaF solution, you have an initial concentration of 0.15 M of F-

  • You can most likely assume that x << 0.15 + x


Predicting precipitation

Predicting precipitation

  • Recall reaction quotient, Qc

    • Same calc as equilibrium constant, but system is not necessarily at equilibrium

  • If Qc < Kc, reaction goes forward

  • If Qc = Kc, reaction is at equilibrium

  • If Qc > Kc, reaction goes reverse

  • Ion product is Qcfor a solubility reaction

    • Reverse means the mixture will precipitate, since the solid dissociates in the forward direction


Precipitation prediction

Precipitation prediction

  • [Ca2+] = 0.0025 M

  • [C2O42-] = 1.0 x 10-7M

  • Will calcium oxalate precipitate? Ksp = 2.3 x 10-9

  • Calculate ion product

  • Compare to solubility product constant


  • Login