25. Introduction to Aqueous Solutions

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Session Overview

Modules	Aqueous Solutions
Concepts	solute, solvent, solution, solubility rules, solubility product
Keywords	water, mixture, colloid, ionic compound, van der Waals force, Madelung constant, suspension, dispersion, molarity, crystallization, miscibility, precipitation, equilibrium constant, saturation, conductivity, common ion effect, homogenization, Arrhenius
Chemical Substances	carbon tetrachloride (CCl₄), potassium permanganate (KMgO₄), silver chloride (AgCl)
Applications	water desalinization, glass manufacturing, bulk metallic glass

Prerequisites

Before starting this session, you should be familiar with:

The Bonding and Molecules module (Session 7 through Session 12)
Chemistry of glasses (Amorphous Materials module), in Session 21 and Session 22

Learning Objectives

After completing this session, you should be able to:

Define what makes an "aqueous solution."
Explain the behavior of ionic compounds in water.
Calculate molarity of a solution.
Predict the solubility of different combinations of solutes and solvents, given the chemical properties of those compounds.
Explain the dynamics of solutions using the concepts of equilibrium constant, solubility product, and common ion effect.

Reading

Book Chapters	Topics
[A&E] 13.1, "Factors Affecting Solution Formation."	Forming a solution; roles of enthalpy and entropy
[A&E] 13.2, "Solubility and Molecular Structure."	Factors affecting solubility; molecular interactions in liquids; solutions of solids; solubility of ionic substances
[A&E] 13.3, "Units of Concentration."	Molarity and mole fraction as measures of concentration
[A&E] 17.1, "Determining the Solubility of Ionic Compounds."	Solubility product K_sp, ion product, common ion effect
[A&E] 17.4, "Solubility and pH."	Acid-base equilibriua effects on solubility; basic, acidic, and amphoteric oxides; using pH for selective precipation

Lecture Video

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Resources

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Transcript (PDF)

Lecture Summary

This session surveys the chemistry of aqueous solutions, in which ionic compounds are dissolved in liquid water as a solvent. The rule "like dissolves like" means that a solute tends to dissolve best in a solvent with similar chemical structure. Molarity is defined as a measure of solubility, and conventions for classifying substances as soluble and insoluble are presented. The session also defines and examines the importance of equilibrium constant K and solubility product K_sp, and the common ion effect.

The class ends with a discussion of the properties of amorphous glasses, including recent advances in fabrication and product manufacturing using bulk metallic glasses.