Heterogeneous mixtures: definition, characteristics and examples.

A summary of the characteristics of heterogeneous mixtures, with several examples and descriptions.

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

Some substances are made up of a single type of element or substance, such as gold or silver, but many others 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, the latter being the ones we are going to talk about in this article. throughout this article.

What is a heterogeneous mixture?

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

In contrast to 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 some subtypes of mixtures require the use of microscopes). The substances that are part of the heterogeneous mixture can be in any state of matter, whether 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 dispersant, this is a type of mixture in which one of the components remains suspended in another. As a general rule, this type of mixture is not stable, and its components tend to separate, forming sediments unless other components are added to contribute to their stabilization.

We can find many examples of heterogeneous mixtures in nature or among the products that we use in our nature or among the products we use on a daily basis: smoke or air pollution, air itself, 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 their 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 their components. Although in some cases these mixtures separate by themselves by sedimentation (think for example of a mixture of water and oil), in some cases it may be necessary to use some kind of procedure to separate their components.

In this sense, we can achieve such separation by simple filtrationespecially 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 could separate the non-soluble metallic components from a liquid) or centrifugation (taking advantage of the centrifugal force, the separation of the components with a different weight is forced.

Dispersions or colloidal mixtures: a subtype of heterogeneous mixture.

Another type of mixture that is technically a heterogeneous mixture, although it has characteristics that also bring it close to homogeneous mixtures, and in fact is sometimes classified separately as an intermediate point between homogeneous and heterogeneous mixtures, are colloids or colloidal dispersions.

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

However, their composition is not the same over their entire surface, so that their components can be distinguished at the 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. present in products such as milk, mayonnaise or rubber..

2. Foams

Foams, such as those visible in beer or shaving foam, are colloidal heterogeneous mixtures in which a gas is dispersed on a liquid..

3. Aerosols

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

4. Solid sols

These are colloid mixtures in which both colloid 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, consisting of a solid that is dispersed in a liquid (gels are semi-rigid solids). Custard or sludge are typical examples.