8.2 Solutions and Their Characteristics 8.3 The Dissolving Process Chapter 8 Solutions 8.2 Solutions and Their Characteristics 8.3 The Dissolving Process

Solution: a homogeneous (one phase) mixture that contains at least one solute and one solvent - the solute is the substance that is dissolved in a solvent - the solvent is the liquid substance in which the solute is dissolved there are different types of solvents but the most common is water which is called an aqueous solution There are heterogeneous mixtures. Oil and water is a classic example of this. Two different phases are visible.

Concentration: the ratio of the quantity of solute to the quantity of solution (solvent) Concentrated solutions have high ratios Dilute solutions have low ratios

Different types of solutions

Properties of Aqueous Solutions can be subdivided at electrolytes or nonelectrolytes - electrolytes are generally high soluble ionic compound that conduct electricity or by pH (acid, base, neutral) Scale goes from 0-14, where 7 is neutral Below 7 acidic Above 7 basic

8.3 The Dissolving Process we can explain some physical properties using intermolecular (between molecules) and intramolecular (between atoms in a molecule) forces water is a polar molecule that is capable of hydrogen bonding thus any polar substances should easily dissolve in water any molecule containing N, O or F has a high probability of forming hydrogen bonds

Ionic compounds tend to dissociate in water This allows them to conduct electricity

Dissociation Equations Show how ionic compounds dissolve in water

Dissociation Equations Complete dissociation equations for 1- barium sulfate, 2- iron (II) phosphate

Dissolving of Molecular Compounds Molecular compounds vary in their ability to dissolve Molecular substances typically experience London forces between molecules This keeps them from dissociating They tend to be molecules that do not contain O, N, or F because these are capable of hydrogen bonding and will mix with water to some extent Those that consist of mainly carbon and hydrogen tend not to dissolve

“Like dissolves Like” Ionic compounds and polar covalent compounds dissolve in polar solvents as a result of solute-solvent attractions A non-polar solute will generally dissolve in a non polar solvent

Surfactants Oil and water can mix together in the presence of a surfactant A surfactant is a substance that acts on the surface of a liquid and reduces surface tension The surfactant works to break hydrogen bonds at the surface that keep water and oil separated

Micelles Detergents and soaps form Micelles which are able to trap grease and remove it from an object