1.7.7

Introduction to Solubility Equilibria

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Introduction to Solubility Equilibria

Solubility equilibria are established when the dissolution and precipitation of a solute species occur at equal rates.

Illustrative background for Solubility product
Illustrative background for Solubility product
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Solubility product

  • The solubility of a substance can vary from essentially zero (insoluble or sparingly soluble) to infinity (miscible).
  • A solute with finite solubility can yield a saturated solution when it is added to a solvent in an amount exceeding its solubility.
    • This results in a heterogeneous mixture of the saturated solution and the excess, undissolved solute.
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Example

  • For example, a saturated solution of silver chloride is one in which the equilibrium shown above has been established.
  • In this solution, an excess of solid AgCl dissolves and dissociates to produce aqueous Ag+ and Cl ions at the same rate that these aqueous ions combine and precipitate to form solid AgCl.
    • Because silver chloride is a sparingly soluble salt, the equilibrium concentration of its dissolved ions in the solution is relatively low.
Illustrative background for 𝐾<sub>sp</sub>Illustrative background for 𝐾<sub>sp</sub> ?? "content

𝐾sp

  • The equilibrium constant for solubility equilibria such as this one is called the solubility product constant, 𝐾sp, in this case:
    • AgCl(s)⇌Ag+(aq)+Cl(aq)
    • 𝐾sp=[Ag+(aq)][Cl(aq)]
  • Recall that only gasses and solutes are represented in equilibrium constant expressions, so the 𝐾sp does not include a term for the undissolved AgCl.
Illustrative background for Interpreting 𝐾<sub>sp</sub>Illustrative background for Interpreting 𝐾<sub>sp</sub> ?? "content

Interpreting 𝐾sp

  • A 𝐾sp value of greater than one means a salt is soluble.
    • Calculating 𝐾sp is covered in the next section.

Jump to other topics

1Physical Chemistry

1.1Atoms, Molecules & Stoichiometry

1.2Atomic Structure

1.3Chemical Bonding

1.4States of Matter

1.5Chemical Energetics

1.6Electrochemistry

1.7Equilibria

1.8Partition Coefficient

1.9Reaction Kinetics

2Inorganic Chemistry

3Organic Chemistry & Analysis

3.1Introduction to Organic Chemistry

3.2Hydrocarbons

3.3Halogen Derivatives

3.4Hydroxy Compounds

3.5Carbonyl Compounds

3.6Carboxylic Acids & Derivatives

3.7Nitrogen Compounds

3.8Polymerisation

3.9Analytical Techniques

3.10Organic Synthesis

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