The concept, process, principle, and precautions of extraction

Principle: A solute is extracted from a solution composed of one solvent and another solvent.

Instruments: separating funnel, beaker.

Steps: Verify that the separating funnel is not leaking.

Measure 10ml of iodine saturated solution and pour it into the separating funnel, inject 4ml of CCL4, and close the cork.

Press down on the mouth of the separating funnel with your right hand, hold the piston with your left hand, and turn the separating funnel upside down and shake vigorously.

Place the separating funnel on an iron rack and let it stand.

After the liquid is stratified, open the glass stopper on the separating funnel, release the lower solution from the lower port, and pour the upper solution from the upper port.

Precautions: a Check whether the separating funnel is leaking.

b Extractants: immiscible and non-reactive.

c The upper solution is poured out from the upper mouth, and the lower solution is released from the lower mouth.

Filtration: A method of separating solubles from insoluble substances by using the different solubility of mixtures. It is necessary to use beakers, glass rods and funnels, pay attention to one sticker, two low and three leaning;

Evaporation: Using the principle that the solubility of the solid solute does not change much with the change of temperature, the solute is precipitated by evaporating the solvent. Alcohol lamps, iron frames, evaporation dishes, glass rods, etc. are required, and direct heating of evaporation dishes should be noted; Glass rods are used for agitation, accelerating evaporation and preventing splashing; When heated to a large number of crystals precipitated, heat with waste heat;

Distillation: Separation is carried out using different boiling points in liquid mixtures. The key is to use different cooling methods for different boiling point ranges, such as condensation water in and out, air condensation, etc.;

Extraction: A method of separating solutes with different solubility in two immiscible solvents. It is mainly the use of a separating funnel, which is suitable for leak detection before application, and the lower liquid flows out of the lower mouth first, and the upper liquid is poured out of the wound.

The selection principle of the extractant is also the focus of the investigation, and it should be noted that the extractant and the original solvent are inmiscible and non-reactive, and the solubility of the solute in the extractant is much greater than that in the original solvent.

These are common separation methods, and they all operate using different physical properties.

Extraction Operating Procedure:

An extractant that does not dissolve with each other is added to the solution to be separated to form two liquid phases that coexist. The difference in the solubility of each component between the original solvent and the extractant is used to make them unequal in the two liquid phases, and the separation between the components is realized through the separation of the two liquid phases.

For example, if the aqueous solution of iodine is extracted with carbon tetrachloride, almost all of the iodine is transferred to carbon tetrachloride, and the iodine can be separated from a large amount of water.

Precautions for extraction:

1. Check for leakage before use.

2. When oscillating, hold the separating funnel with both hands, press the cork with your right hand, lay it flat, and oscillate it up and down.

3. Before discharging, open the cork.

4. When discharging liquid, remember that the lower layer is a dense liquid and release it from below. The upper layer is a liquid with a relatively low density, which is poured from above.

5. It should be cleaned immediately after use.

Principles of Extraction:

The difference in solubility or partition coefficient of a substance in two immiscible (or slightly soluble) solvents causes a substance to be transferred from one solvent to another. After repeated extractions, most of the compounds were extracted.

The law of partition is the main basis for the theory of extraction method, and substances have different solubility to different solvents. At the same time, in two immiscible solvents, when a soluble substance is added, it can be dissolved in two solvents respectively, and experiments have proved that at a certain temperature, the ratio of the compound in the two liquid layers is a fixed value when the compound and the two solvents do not decompose, electrolyze, associate and solvate the two solvents.

1. The principle and steps of extraction

1. The principle of extraction: using the different solubility of substances in immiscible solvents, one solvent is used to extract the substance from the solution composed of it and another solvent.

2. The principle of extractant selection: it is incompatible with the original solvent, and can not react with the solute and the original solution, and the solubility of the solute in the extractant is much greater than that in the original solvent.

3. Common extractants: benzene, gasoline (or kerosene) - insoluble in water, less dense than water; $ccl 4$ — insoluble in water, denser than water.

4. Extraction steps: add extractant $ to$ **Extract $ to$ stand stratification $ to$ separation.

5. Precautions: Before using the separating funnel, the town should check whether there is any leakage.

6. Test method: close the piston at the bottom of the separating funnel, add an appropriate amount of distilled water, stand still, no water flows down, indicating that the piston does not leak, plug the glass plug on the upper mouth of the separating funnel, invert, observe whether there is water leakage, if there is no water leakage, rotate the glass plug 180°, and then invert to observe, if there is still no water leakage, the glass plug does not leak.

2. Examples of extraction

The operation of separating different components by using the difference in the solubility of each component of a liquid mixture in the liquid is called

A, Distillation B, Extraction C, Absorption D, Desorption.

Answer: B Analysis: Extraction refers to the use of a substance with different solubility in an immiscible solvent to extract a substance from a solution composed of another solvent, so the answer is B.

The principle of extraction is to extract most of the compounds after repeated extractions.

The difference in solubility or partition coefficient of a substance in two immiscible (or slightly soluble) solvents is used to transfer a substance from one solvent to another. After repeated extractions, most of the compounds were extracted.

Extraction Introduction: Extraction, also known as solvent extraction or liquid-liquid extraction, also known as extraction, is a unit operation that uses the different solubility of the components in the system to separate the mixture. That is, it is a method of transferring solute substances from one solvent to another solvent by using the difference in solubility or partition coefficient of substances in two immiscible (or slightly soluble) solvents.

It is widely used in chemical, metallurgical, food and other industries, and is commonly used in petroleum refining industry. In addition, the operation of separating the two immiscible liquids after extraction is called dispensing. Solid-liquid extraction, also known as leaching, uses solvents to separate components in a solid mixture, such as sugars in sugar beets with water; The soybean oil in soybeans is soaked with alcohol to increase oil yield.

Although extraction is often used in chemical tests, its operation process does not cause a change in the chemical composition of the extracted substance (or chemical reaction), so the extraction operation is a physical process.

Extraction is one of the methods used in organic chemistry laboratories to purify and purify compounds. By extraction, the desired substance can be extracted from a solid or liquid mixture. <>

First of all, I recommend you to read this book "The Extraction of Rare Earths and Solvents", edited by Xu Guangxian (the father of rare earths).

Extraction is a physical change process, chemical change process, depending on the extractable, extractant, complexing agent, impurities, acid-base ions, etc., for example, the example of CCI4 extraction I2 is physical extraction, which depends on the different solubility of the extractable in the two phases. The extraction of UO2 (NO3)2 by TBP (tributyl phosphate) is chemical extraction, and the two form a complex.