Heterogeneous mixtures: definition, characteristics and examples

There are many substances that exist in our world, made up of multiple molecules that come together in various ways to generate complex compounds and structures.

Some substances are made up of the same type of element or substance, such as gold or silver, but others many are compounds formed by multiple types of substances, generating various types of mixtures with different properties.

Although they could be classified in multiple ways, as a general rule we can find homogeneous mixtures or heterogeneous mixtures, being the latter about which we are going to talk throughout this article.

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What is a heterogeneous mixture?

A heterogeneous mixture is understood to be any substance or material formed by the union of two more substances, which are combined without joining and in a non-uniform way. In this type of mixture, therefore, the components are distributed unevenly: if we take two fragments or parts of it it is probable that we do not observe the same proportions in the compound and even the same components.

Unlike homogeneous mixtures, all components of homogeneous mixtures retain their individual properties and are separable and even directly visible, usually even to the naked eye (although in some mix subtypes it is necessary to use microscopes). The substances that are part of the heterogeneous mixture can be in any state of matter, be it solid, liquid or gas.

Most heterogeneous mixtures are suspensions, which usually tend to be mixtures of one or more liquids and a liquid and a solid. Formed by a dispersed phase or non-soluble particles and a dispersing one, it is a type of mixture in which one of the components remains suspended in another. As a general rule, these types of mixtures are not stable, and their components tend to separate, forming sediments unless other components are added that contribute to their stabilization.

We can find multiple examples of heterogeneous mixtures in nature or among the products we use on a daily basis: smoke or air pollution, the air itself, the sand on the beach, granite, ice cream, Roquefort cheese, blood, most drugs or mixtures such as water and oil, Caesar sauce or salads.

How can its components be separated?

As we have mentioned, one of the properties of heterogeneous mixtures lies in the fact that it is possible to identify and even separate its components. Although in some cases these mixtures separate by themselves through sedimentation (think, for example, of a mixture of water and oil), in some cases it may be necessary to use some type of procedure to separate their components.

In this sense, we can achieve such separation by simple filtration, especially when we are dealing with a heterogeneous mixture in which there is a solid and a liquid component. Other methods can be magnetization (with which we would be able to separate non-metallic components from a liquid). solubles or centrifugation (taking advantage of the centrifugal force forces the separation of the components with a weight different.

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Colloidal dispersions or mixtures: a subtype of heterogeneous mixture

Another type of mixture that is technically a heterogeneous mixture despite the fact that it has characteristics that also bring it closer to homogeneous ones, and that In fact, they are sometimes classified separately as an intermediate point between a homogeneous and heterogeneous mixture, they are colloids or dispersions colloidal.

Colloids are homogeneous-appearing mixtures. composed of two or more elements in which one or more of these are permanently suspended in the other, the former being the colloidal particle (also called the dispersed phase) and the latter a fluid (or dispersing phase). In other words, these are mixtures in which one or more of the components remain in the form of specks or microscopic drops that remain stable and do not separate.

However, its composition is not the same throughout its surface, so that its components could be distinguished at a microscopic level. Within this type of mixtures we can find different subtypes.

1. emulsions

Emulsions are mixtures in which a liquid is dispersed in a solid or another liquid, something present in products such as milk, mayonnaise or gum.

2. foams

Foam, such as that visible in beer or shaving foam, are colloidal heterogeneous mixtures in which a gas is dispersed over a liquid.

3. Aerosol sprays

In aerosols the dispersed phase can be either a liquid or a solid, while the dispersing phase is a gas. Among this type of mixtures we can find such common elements as smoke, fog or clouds,

4. solid suns

These are colloidal mixtures in which both colloidal particles and fluid are solid elements. This is the case of alloys such as steel.

5. gels and sols

Gels and sols are also a colloidal mixture, made up of a solid that is dispersed in a liquid (gels are semi-rigid solids). Flan or mud are typical examples.