In chemistry, a mixture refers to the union of at least two substances , in varying proportions, without there being a chemical combination. 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, which are the following:
- Homogeneous Mixtures : In this type of mixtures it is very difficult to identify which are the elements that compose them. In this way, the human being can only detect a single physical phase. Within the homogeneous liquid substances, called “solutions”, the solvents of the solutes are identified. While solutes are low in quantity and are almost always liquid, solvents predominate in proportion. Eg wine , beer , gelatin , water and alcohol .
- Heterogeneous Mixtures : Unlike homogeneous mixtures, in these it is very easy to identify, even to the naked eye, which are the different components that make them up. This makes it much easier to separate these mixtures. Eg 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 naphtha.||Potatoes and egg.|
|Stones and wood.||Water and stones.|
|Papers and tapes||Milk with marshmallows.|
|Water and paraffin||Cookies with sweet and butter.|
|French fries and peanuts.||Wood and stones|
Techniques to separate mixtures
Over time, different techniques have been developed to separate the components that make up the mixtures.
Some of them are:
- Screening : This is used for solid mixtures that are in the form of grains. What is done then is to pass them through one or several sieves, as necessary. In this way, while one element remains in the sieve, the rest falls.
- Magnetic separation (or magnetization ): This technique is very limited since it can only be applied in those mixtures in which some of its components have magnetic properties . Then, these are captured by some magnet.
- Filtration : At the time of wanting to separate those mixtures that contain non-soluble solids and liquids, you can choose this option, which consists of using a funnel made of filter paper on the inside. Thus, the elements that pass through the funnel will be separated from those that are retained in it.
- Crystallization and precipitation : In this technique, the temperature of the mixture rises and thus it is possible to concentrate it, then filter it and place it in a crystallizer, where it is allowed to rest until the liquid evaporates. Once this happens, the solid part is preserved, in the form of crystals, on the crystallizer. As it is observed, this is the appropriate technique to separate mixtures composed by a solid solute dissolved in a solvent.
- Decantation : To separate liquids that have different densities , this technique is used, which consists of a separating funnel in which the mixture to be separated is placed. After letting it rest for a while, the densest part will be located at the bottom. What is done then is to open the key of the funnel of decantation, until all the substance of greater density falls, while the rest remains in said funnel.
- Distillation : Finally, this technique consists of boiling the mixture to be separated , as long as it is composed of different liquids that are soluble among each other. What happens is that different liquids require different boiling temperatures, which allows them to capture their vapors in test tubes, as they evaporate, and then return them to liquid state.