Solutions (continued)

True solution

They are translucent homogeneous mixtures, with average particle diameter between 0 and 1 nm.

Examples: sugar in water, table salt in water, hydrated alcohol.


They are homogeneous mixtures that have giant molecules or ions. The average diameter of its particles is from 1 to 1,000nm. This kind of mixture easily scatters light, so they are opaque, not translucent.

They may be solid, liquid or gaseous.

The term colloid comes from the Greek and means "cola". It was proposed by Thomas Grahm, in 1860, to name them substances such as starch, glue, gelatin and albumin, which diffused slowly in water, compared to true solutions (water and sugar, for example).

Although colloids look homogeneous to the naked eye, at the microscopic level they are heterogeneous. This is because they are not stable and almost always precipitate.

Examples: mayonnaise, shampoo, milk of magnesia, mist, gelatin in water, milk, cream.


Suspension They are mixtures with large clusters of atoms, ions and molecules. The average particle size is over 1,000nm.

Examples: earth suspended in water, black smoke (coal particles suspended in the air).