What is a mixture?

In chemistry, What is a mixture is a material made up of two or more components joined physically, but not chemically. This means that no chemical reaction occurs between them, that is, each component maintains its identity and chemical properties, even when we cannot distinguish one component from the other.

The components or phases of a mixture are mechanically or physically linked. For this reason, their physical properties, such as boiling or melting point, are often altered.

However, since there are no permanent chemical changes, it is possible to use physical separation mechanisms to extract each of the components of a mixture. These physical mechanisms are usually thermal (when they involve heat) or mechanical (when they involve displacement or movement).

Mixtures are mixed forms of matter that are extremely common in everyday life, and many of the materials we use are the result of a mixing or mixing procedure. The components of a mixture can be in different states of aggregation (solids, liquids, gases, plasmas, or combinations between them).

Types of mixtures

The mixtures are classified according to how feasible it is to identify their different components at a glance.

• Homogeneous mixes. They are those in which the components cannot be distinguished. They are also known as solutions, and are made up of a solvent and one or more solutes. And as we have said, the phases are impossible to identify with the naked eye.
• Heterogeneous mixtures. They are those in which the components can be easily distinguished, because they have a non-uniform composition, that is, their phases are integrated unevenly and irregularly, and therefore it is possible to distinguish their phases with relative ease. Depending on the size of the particles of its components, we can speak of two types of heterogeneous mixtures:

Coarse mixtures or coarse dispersions. They are those in which the size of the particles is visible to the naked eye.

Suspensions or colloids. They are those in which one phase is normally fluid (gaseous or liquid) and the other is made up of particles (generally solid) that remain suspended and settle over time.

Examples of homogeneous mixtures

Here are some examples of homogeneous mixtures:

The air. The common gas that we breathe every day is a mixture of pure gaseous substances (such as oxygen, nitrogen and argon, among others) that are impossible to perceive with the naked eye and that, together, are usually odorless.

Alcoholic beverages. Like cocktails, they consist of two or more liquids (or even solids) mixed until they acquire a uniform appearance and, although we can savor their members, we cannot point them out with the naked eye.

The water with sugar. What we usually given to people who are decompensated, is a dilution of a solid (sugar) in a liquid (water), to the point that the difference cannot be appreciated.

Must Read: What is a dissolution?

Metal alloys. Like the stainless steel from which some knives are made, they are obtained by mixing iron with carbon and other metallic components, so that the mixture acquires the combination of its properties. To do this, they must be melted to a liquid state, then mixed and allowed to solidify.

The amalgams. As the dentist used in the past, they used to be a mixture of mercury and some other metal, turned into a uniform and malleable paste, which then hardened when solidifying.

Shaving foam. It is a mixture of water, soaps, glycerin and menthol, often accompanied by gases (if it comes in a spray).

The blood. It is also a homogeneous mixture of an immense number of liquid, solid and gaseous compounds, which we simply appreciate as a more or less thick red liquid.

Examples of heterogeneous mixtures

Here are some examples of heterogeneous mixtures:

Aerosols. Like deodorants or spray paint, they are made up of a mixture of liquid and gas, which are ejected from the container at the same time, but then the gas disperses and the liquid remains on the sprayed surface. It is a colloidal mixture.

Gravel or gravel. It is a mixture of two or more types of stone in small pieces, which can be distinguished with the naked eye. It is a case of coarse dispersion.

A salad. It is another perfect example of coarse dispersion, since we can see each of its components with the naked eye but they all work together: vegetables, oil, fruits, sometimes meats, etc.

Water and oil. It is also an example of a heterogeneous mixture in which we can identify both phases, although in this case it is a liquid-liquid suspension.

Some medications In whose packages it is suggested that we shake them before use, they are cases of suspensions in which the solid precipitates to the bottom over time, and that is why we must shake it so that it dissolves again, making the distinction between one and the other temporarily inappreciable.

The concrete. It is a mixture of water, sand and cement in specific proportions that, once solidified and dried, acquires its hardness and uniformity.

Pure substances

Pure substances are those that are not the result of a mixture, but are composed of a single phase and, therefore, cannot be separated into their components by physical methods. In addition, they have a stable chemical composition and are chemically uniform.

A pure substance does not necessarily have to be composed of only one type of chemical element. Pure substances can be classified into:

Simple substances. They are those composed of a single type of chemical element (which does not mean that they are composed of a single atom). For example: oxygen (O2), nickel (Ni).

Compound substances. They are those composed of more than one type of chemical element. For example: water (H2O), carbon dioxide (CO2).

The only way to separate the elements of a pure substance is using chemical methods, that is, transforming it into other substances or directly into its chemical elements.

It is necessary to clarify that absolute purity does not exist. In the world we live in, substances exist in nature in the form of certain mixtures, or in other words, with a certain level of impurities. However, impurities can be removed to achieve the desired or permitted degree of purity of the substance.

Examples of pure substances: copper (Cu), silver (Ag), gold (Au), glucose (C6H12O6), oxygen (O2), water (H2O).