Heterogeneous Mixtures

1. Suspensions

Suspension – a mixture containing particles that settle out if left undisturbed.

Particles are too large to be dissolved. Particles are greater than 1000 nm in diameter. They can be filtered. Examples : muddy water, many “liquid”

medicines that require “shaking,”

2. Colloids Colloid – Heterogeneous mixture of intermediate

size particles. They do not dissolve or settle. These particles remain dispersed in the

solution, they “float” and are suspended. Particles cannot be removed by filtering. They are between 1 nm and 1000 nm in

diameter. The most abundant substance in a colloid is the

dispersion medium.

If you stir an electrolyte into the colloid, it will cause the particles to settle out.

“Flocculents” bring the colloid particles together and the mass becomes so great that it forms a suspension.

Examples of colloids include smog, fog, milk, mayonnaise, marshmallow, smoke, clouds.

Colloids are classified as : sol, gels, emulsions, foam, and aerosols.

Sol – a solid dispersed in a liquidExamples : paints, blood

Gel – a solid network extending throughout a liquid.Example : gelatin (jello)

Liquid emulsion – liquid dispersed in a liquidExamples : milk, mayonnaise

Solid emulsion – liquid dispersed in a solidExamples : cheese, butter

Foam – gas dispersed in liquidExamples : shaving cream, whipped cream,

beaten egg white Solid Foam – Gas dispersed in a solid

Examples : marshmallow, soaps that float Solid aerosol – solid dispersed in gas (air)

Examples : smoke, air borne particulate matter, auto exhaust

Liquid aerosol – liquid dispersed in gas (air) Examples : fog, mist, clouds, aerosol spray

Brownian motion – the random, erratic motion of colloid particles.Caused by the polar areas of the molecules.

They attract and repel each other, keeping them in constant motion.

Tyndall Effect – particles in a colloid are large enough to scatter light.

Turbidity – how cloudy the water is.

ColloidType

Dispersed substance

Dispersing Medium Examples

Solid Sol Solid Solid Colored gems

Sol Solid Liquid Blood

Gel Solid Network Liquid Gelatin

Solid Emulsion Liquid Solid Butter, Cheese

Liquid Emulsion Liquid Liquid Milk, mayonnaise

Solid Foam Gas Solid Marshmallow, soaps that float

Foam Gas Liquid Shaving cream, whipped cream

Solid Aerosol Solid Gas Smoke, dust in air

Aerosol Liquid Gas Fog, aerosol spray, clouds

ColloidType

Dispersed substance

Dispersing Medium Examples