Suspension is a heterogeneous mixture of substances (solids, liquids or gases) in which the solute particles are large enough (usually larger than 1 micrometer) for sedimentation. A suspension is broadly divided into two parts, the dispersed material (usually a solid) and a dispersion medium (can be solid, liquid or a gas). The dispersed particles in a suspension are visible to the naked eye and can be easily separated from the mixture by running it through filter paper. If allowed to stand still for some time, the suspended particles automatically settle down. Muddy water, flour dissolved in water, dust particles suspended in the air are some common examples of suspension.
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A colloid is a substance (usually solid) microscopically dispersed throughout another substance (solid, liquid or gas) and the mixture is termed as a colloidal solution. A colloidal system consists of two phases, an internal phase (or dispersed phase) and a dispersion medium (or continuous phase). The size of the dispersed phase particles is very small (1 to 1000 nanometres) and are normally invisible under a microscope. However, their presence gives the solution a hazy look as milk and fog are two of the most common examples of a colloidal solution.
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