Colloids in Chemistry

Study Notes

Colloids Overview

Colloids are mixtures where dispersed particles are intermediate in size, larger than molecules but smaller than suspension particles.
Light scatters when it passes through a colloid, demonstrating the Tyndall effect.

Examples of Colloids

Common examples include milk, fog (smog combined with smoke), and whipped cream.

Types of Colloids

Colloids can be categorized into several types: emulsions, foams, sols, gels, and aerosols.
Classification is based on the dispersion of one substance within another and requires identification of the dispersed phase and dispersing medium.

Colloid Classification Table

Dispersed Phase	Dispersing Medium	Colloid Type	Examples
Solid	Solid	Solid sol	Colored glass (e.g., ruby glass), gemstones
Solid	Liquid	Sol	Blood, pigmented ink, paint
Solid	Gas	Solid aerosol	Smoke, dust
Solid	Solid	Solid foam	Marshmallow, Styrofoam, pumice
Gas	Liquid	Foam	Whipped cream, shaving cream, egg white foam, soap suds

Suspension

Mixing sand with water demonstrates that sand does not dissolve, creating a heterogeneous mixture called a suspension.
In a sand and water suspension, solid sand particles settle at the bottom when undisturbed, although a few may remain visible in the water.
Sand particles in a suspension are larger than solute particles in a solution and remain insoluble in water.
Some suspensions may appear to dissolve at first but eventually separate, as seen in muddy water, unfiltered brewed coffee, and powdered drinks mixed with water.
Unlike homogeneous solutions, particles in suspensions only blend without entirely dissolving in the liquid.
For effectiveness, suspension medicines must be shaken before use to ensure even distribution and potency.

Colloid

A colloid is another type of heterogeneous mixture characterized by properties between homogeneous and heterogeneous mixtures.
Despite its uniform appearance, a colloid is cloudy or may appear opaque, indicating the presence of suspended particles.
Colloids are heterogeneous because they contain tiny particles that are scattered and suspended within the mixture.

Big Idea

A suspension consists of insoluble solids that settle at the bottom of the liquid when left undisturbed, distinguishing it from solutions where solutes fully dissolve.

Description

Explore the fascinating world of colloids, including their definitions and examples. This quiz covers key concepts such as the Tyndall effect and different types of colloidal mixtures. Test your understanding of colloidal systems and their characteristics.