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Solutions, Suspensions and Colloids

  1. Solutions

Examples: salt water, vinegar

  • Homogenous mixture

  • Dissolves evenly

  • Particles don’t settle down to the bottom

  • Particle size 0.01-1 nm (nanometre)

  • Can’t be separated by filtration *

  • Particles don’t scatter light

  1. Suspensions

Examples: chalk in water, muddy water

  • Heterogeneous mixture

  • Doesn’t dissolve

  • Particles settle to bottom

  • Particle size >1000nm

  • Particles separate on standing **

  • Particles scatter light

  1. Colloids

Examples: milk, whipped cream, gelatin

  • Heterogeneous mixture

  • BUT it is evenly distributed ***

  • Particle size 1-1000nm

  • Doesn’t separate on standing

  • Can’t be separated by filtration

  • Particles scatter light (Tyndall effect)

*What does it mean to be able/unable to be separated by filtration?

Filtration: the process of separating insoluble solids (stuff that doesn’t dissolve in water) using a filter.

If the particles are unable to be separated by filtration, it means they can’t be filtered out, meaning they’re fully dissolved.

**What does it mean when particles separate on standing?

It means that if the mixture is left untouched, the particles will slowly settle to the bottom because they are too heavy to float.

***Why are colloids heterogeneous if their particles are evenly distributed?

They have not dissolved like homogenous mixtures, they’re just small enough to stay floating.

****What is the Tyndall effect?

The Tyndall effect is when colloids scatter light in all directions.