20 Examples of Heterogeneous Mixtures

In chemistry, a mixture It is a combination of at least two substances, in equal or variable proportions, without there being a combination at the chemical level. A mixture is not a chemical reaction. This means that each of the substances that make up the mixtures contribute their properties to the whole.

Within the mixtures, two variants can be identified:

  • Homogeneous mixtures. In this type of mixtures it is very difficult to identify which are the compounds that compose them. In this way, the human being can only detect a single physical phase. Within liquid homogeneous mixtures, called “solutions”, solvents are differentiated from solutes. While the solutes are in low quantity and are almost always liquid, the solvents predominate in proportion. For example: wine, beer, jelly, water and alcohol.
  • heterogeneous mixtures. Unlike homogeneous mixtures, in heterogeneous mixtures it is very easy to identify, even with the naked eye, which are the different components that make them up. This makes it much easier to separate these mixtures. For example: water and oil / water and sand.

Examples of heterogeneous mixtures

Lettuce and tomato salad Water and sand Water and oil Helium and air Air and earth Soup with noodles Rice and beans Water and sugar Vinegar and oil Sausages with mayonnaise Water and gasoline Potatoes and eggs Stones and wood Water and stones Paper and tape Milk with marshmallows Water and paraffin Cookies with butter and butter Potato chips and peanuts Wood and stones

Techniques for separating mixtures

Over time, different techniques have been developed to separate the components that make up the mixtures. Some of them are:

  • screening. This technique is used to separate solid mixtures that are in the form of grains of different sizes. They are passed through one or more sieves, as necessary. In this way, while one component remains on the screen, the rest passes through its holes.
  • magnetic separation (either magnetization). This technique is very limited since it can only be applied to separate those mixtures in which some of its components have magnetic properties. So, these components are attracted by the magnetic field of some magnet, while the components that do not have magnetic properties are not attracted.
  • Filtration. When you want to separate those mixtures that contain insoluble solids and liquids, you can choose this option, which consists of using a funnel made of filter paper on the inside. Thus, the components that pass through the funnel will be separated from those that remain retained in it.
  • crystallization and precipitation. In this technique, the temperature of the mixture is raised and thus it is possible to concentrate it and then filter it and place it in a crystallizer, where it is left to rest until the liquid evaporates. Once this happens, the solid part is preserved in the form of crystals on the crystallizer. This is the proper technique to separate mixtures composed of a solid solute dissolved in a solvent.
  • settling. To separate liquids that have different densities and are immiscible, this technique is used. The mixture to be separated is placed in a separating funnel. After letting it rest for a while, the densest part will be located at the bottom. Then, the stopcock of the separatory funnel is opened, until all the substance of greater density falls out, while the rest remains in the funnel.
  • Distillation. This technique consists of increasing the temperature of the mixture to be separated. The mixture must be composed of different liquids that are soluble in each other. What happens is that different liquids have different boiling temperatures, so as the temperature increases, the liquid with the lowest boiling temperature will first go into the vapor phase and then condense in another container. In this way, it will be separated from the liquid that has a higher boiling temperature.
  • chromatography. It is a technique for separating very complex mixtures, which are difficult or impossible to separate by previous separation methods. It is based on the displacement of the sample to be separated through a stationary phase (which can be paper or a resin, for example). For it to move, the sample must be transported by a mobile phase (which can be liquid or gaseous). The separation of the components occurs due to the difference in affinity of each one for both phases. The components most related to the stationary phase are retained in it, while the others flow in the mobile phase.

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