In the mixture, the starting substances are included unchanged. In this case, often the original substances become unrecognizable, because the mixture exhibits different physical properties compared to each isolated starting substance. When mixed, however, no new substance is produced.

The specific qualities of a mixture, such as density, boiling point or color, depend on the mixture ratio (mass ratio). A mixture of two metals obtained by mixing their melts is called an alloy. In another connection, one speaks of a conglomerate. Colloidal solutions are in the middle between homogeneous and heterogeneous mixtures. These liquids are mixed with solid particles, each of which consists of a small number of molecules. Therefore, such a mixture behaves like a solution.

If they want to separate the mixture into pure substances, then they use some physical qualities. This results in the selection of an appropriate separation method.

Homogeneous and heterogeneous mixtures

Various types of mixtures can be classified into 2 groups:

• Heterogeneous mixtures are not completely mixed, since pure substances exist in clearly delimited phases, that is, they are multiphase materials.
• Homogeneous mixtures are molecular level mixed pure substances, that is, these are single-phase materials.

Homogeneous mixtures are divided according to their state of aggregation into three groups:

• gas mixtures;
• solutions;
• solid solutions.

Heterogeneous mixtures of two substances can be divided according to their state of aggregation into the following groups:

A measure indicating the proportion of substances in a mixture is concentration.

The difference between pure substances and mixtures

The simplest such distinction is for gases. Pure complex substance(for example, water), consists of one type of molecules, and a mixture of gases - from several types (for example, oxygen and hydrogen molecules). A mixture of gases can be separated physical methods(for example, diffusion), but a complex substance cannot.

With regard to liquid and solid mixtures, everything is not always clear.

Separation of mixtures

There are various methods for separating mixtures. For gases, these methods are based on the difference in velocities or masses of the molecules of the substances included in the mixture.

1. The main methods for isolating substances from a heterogeneous (heterogeneous) mixture:

• upholding

• filtration

• magnet action

2. The main methods for isolating substances from a homogeneous (homogeneous) mixture:

• evaporation

• crystallization

• distillation

• chromatography

see also

Notes

Wikimedia Foundation. 2010 .

See what "Mixture (chemistry)" is in other dictionaries:

Mixture: A mixture (chemistry) is a product of mixing, a mechanical combination of any substances, characterized by an impurity content above a certain limit. For example: combustible mixture, helium-oxygen mixture. Random, disorderly, deprived ... ... Wikipedia

Ash and slag mixture- Ash and slag mixture - a mixture consisting of ash and slag formed at thermal power plants when coal is burned in boiler furnaces. [GOST 25137 82] Ash and slag mixture - a mechanical mixture of dusty fly ash and slag ... ...

- (Eschka mixture) a mixture of two parts of MgO and one part of Na2CO3, a reagent that absorbs sulfur and chlorine oxides well. For example, to determine the sulfur content of coal, a sample of coal is burned with an Eschka mixture. In this case, soluble sulfates are formed ... ... Wikipedia

Mixture activated sfb- - a mixture prepared on water with additives, passed through a rotary pulsation apparatus and subject to cavitation; allows you to get an economic effect by increasing the specific surface of cement and the formation of cement ... ... Encyclopedia of terms, definitions and explanations of building materials

Asphalt mix- - a rationally selected mixture of mineral materials [crushed stone (gravel) and sand with or without mineral powder] with bitumen, taken in certain proportions and mixed in a heated state. [GOST 9128 97] Heading term: Asphalt ... ... Encyclopedia of terms, definitions and explanations of building materials

Mix concrete of a given quality- is a concrete mixture, the required properties and additional characteristics of which are specified by the manufacturer, who is responsible for ensuring these required properties and additional characteristics. [GOST 7473 2010] Term heading: ... ... Encyclopedia of terms, definitions and explanations of building materials

Concrete mix of specified normalized composition- is a concrete mixture of a given composition, the composition of which is determined by a standard or other technical document, for example, production standards. [GOST 7473 2010] Term heading: Concrete properties Encyclopedia headings: Abrasive ... ... Encyclopedia of terms, definitions and explanations of building materials

Mix concrete of a given composition- is a concrete mixture, the composition of which and the components used in the preparation are specified by the manufacturer, who is responsible for ensuring this composition. [GOST 7473 2010] Term heading: Concrete properties Encyclopedia headings: ... ... Encyclopedia of terms, definitions and explanations of building materials

Refractory concrete mix- - a refractory mixture consisting of refractory powders and refractory cement, ready for use after the introduction of the liquid. [GOST R 52918 2008] Term heading: Concreting technologies Encyclopedia headings: Abrasive equipment, ... ... Encyclopedia of terms, definitions and explanations of building materials

Refractory mixture- - unshaped refractory, consisting of refractory powders, ready for use after the introduction of the binder. [GOST R 52918 2008] Refractory mixture - unshaped refractories consisting of refractory powders requiring the introduction of a binder. [GOST ... Encyclopedia of terms, definitions and explanations of building materials

Books

• Fundamentals of general and physical chemistry. Textbook, Eremin Vadim Vladimirovich, Borshchevsky Andrey Yakovlevich. The book is created on the basis of a one-year course `General and Physical Chemistry` for 2nd year students of the Faculty of Physics of Moscow State University. Choosing the level of presentation, we proceeded from the fact that it will be read ...

>> Pure substances and mixtures. Settling. Separation of a mixture of three solids

Pure substances and mixtures

The paragraph will help you:

> realize that absolutely pure substances do not exist;
> distinguish between homogeneous and inhomogeneous mixtures of substances;
> find out in which mixtures the physical properties of the components are preserved, and in which they are not;
> select separation method mixtures of substances depending on its type.

Pure substances and mixtures.

Each substance always contains a certain amount of impurities. A substance that contains almost no impurities is called pure. With these substances work V scientific laboratory, school chemistry room. Note that absolutely pure substances do not exist.

Each substance contained in a mixture is called a component.

Mixtures in which components cannot be detected by observation are called homogeneous.

Most metal alloys are also homogeneous mixtures. For example, an alloy of gold and copper (used to make jewelry) lacks red copper particles and yellow gold particles.

From materials that are homogeneous mixtures of substances, many items for various purposes are made (Fig. 27).

All mixtures belong to homogeneous mixtures. gases, including air. There are many homogeneous mixtures of liquids.

Rice. 27. Items made from homogeneous mixtures

Such a mixture is formed by mixing, for example, alcohol and water.

Give an example of a homogeneous mixture.

Homogeneous mixtures are also called solutions, even if they are solid or gaseous.

For some physical properties homogeneous mixtures differ from their components. Thus, an alloy of tin and lead, used for soldering, melts at a lower temperature than pure metals. Water boils at a temperature of 100 ° C, and an aqueous solution of salt - at a higher temperature. If water is cooled to 0°C, it will begin to turn into ice. A salt solution under these conditions remains a liquid (it freezes at temperatures below 0 ° C). This can be seen in winter, when roads and sidewalks covered with ice are sprinkled with a mixture of salt and sand. Ice melts under the influence of salt; an aqueous solution of salt is formed, which does not freeze in mild frost. And sand is needed so that the road is not slippery.

Rice. 28. Heterogeneous mixture of chalk and water

You know that chalk does not dissolve in water. If its powder is poured into a glass of water, then chalk particles can always be found in the resulting mixture, which are visible to the naked eye or through a microscope (Fig. 28).

Mixtures in which components can be detected by observation are called heterogeneous.

Heterogeneous mixtures (Fig. 29) include most minerals, soil, building materials, living tissues, turbid water, milk and other foods, some drugs and cosmetics.

Give an example of an inhomogeneous mixture.

In a heterogeneous mixture, the physical properties of the components are preserved. So, iron filings mixed with copper or aluminum do not lose their ability to be attracted to a magnet.

Rice. 29. Heterogeneous mixtures:
a - a mixture of water and sulfur;
b - a mixture of vegetable oil and water;
c - a mixture of air and water

Water mixed with sand, chalk or clay freezes at 0°C and boils at 100°C.

Some types of heterogeneous mixtures have special names: foam (for example, foam, soap suds), suspension (a mixture of water with a small amount of flour), emulsion (milk, well-shaken vegetable oil with water), aerosol (smoke, fog).

What are the ingredients in each named mixture?

The material presented above is summarized in Scheme 3.

Scheme 3. Substances and mixtures

It often becomes necessary to separate a mixture in order to obtain its components or to purify a substance from impurities.

There are many methods for separating mixtures. They are chosen taking into account the type of mixture, state of aggregation and differences in physical properties components (scheme 4). Some methods you know from the course of natural history.

Scheme 4. Methods for separating mixtures

Explain what properties of the components make it possible to separate each heterogeneous mixture indicated in the diagram.

Rice. 30. Worker in a respirator

Consider how some methods separation of mixtures.

The filtering process underlies the operation of a respirator, a device that protects the lungs of a person working in a heavily dusty environment. The respirator has filters that prevent dust from entering the lungs (Fig. 30). The simplest respirator is a bandage made of several layers of gauze. A filter that extracts dust from the air is also in the vacuum cleaner.

With the help of a magnet in industry, they enrich iron ore - magnetite.

Due to the ability to be attracted to a magnet, the ore is separated from sand, clay, earth, etc. In this way, iron is extracted from industrial and domestic waste.

An important method for separating homogeneous mixtures of liquids is distillation, or distillation. This method allows you to clear natural water from impurities. The resulting pure (distilled) water is used in research laboratories, in the production of substances for modern technology, in medicine for the preparation of medicines.

1 The term comes from the Latin word distillatio - dripping.

In industry, the distillation of oil (a mixture of many substances, mainly liquids) produces gasoline, kerosene, and diesel fuel.

In the laboratory, distillation is carried out on a special installation (Fig. 31). When a mixture of liquids is heated, the substance with the lowest boiling point boils first. Its vapor leaves the vessel, cools, condenses1, and the resulting liquid flows into the receiver. When this substance is no longer in the mixture, the temperature will begin to rise, and over time, another liquid component will boil. Non-volatile liquids remain in the vessel.

Rice. 31.Laboratory installation for distillation:

a - ordinary;
1 - a mixture of liquids with different temperatures boiling;
2 - thermometer;
3 - water cooler;
4 - receiver
6 - simplified

The separation of various mixtures also occurs in nature. Dust particles settle from the air, and during rain and snow - water droplets, snowflakes. As a result of settling, cloudy water becomes transparent. Water is also purified from insoluble substances when passing through sand. After the evaporation of water, salts remain on the banks of the estuaries, which were dissolved in it. Dissolved gases are released from the water flowing from the well.

1 The term comes from the Latin word condensatio - thickening, compaction.

conclusions

Every substance contains impurities. A substance is considered pure if it contains almost no impurities.

Mixtures of substances are either homogeneous or heterogeneous. In a homogeneous mixture, the components cannot be detected by observation, but in an inhomogeneous mixture it is possible.

Some physical properties of a homogeneous mixture differ from those of the components. In a heterogeneous mixture, the properties of the components are preserved.

Inhomogeneous mixtures of substances are separated by settling, filtering, sometimes by the action of a magnet, and homogeneous mixtures are separated by evaporation and distillation (distillation).

?
29. What types of mixtures exist and how do they differ?

30. Write down the given words and phrases in the appropriate columns of the table below: aluminum, ash, newsprint, mercury, air, iodine tincture, granite, ice from pure water, carbon dioxide, reinforced concrete.

Pure substances	Mixes
	homogeneous	heterogeneous

31. Name a few foods that are solutions.

32. What popular drink, depending on the method of preparation, is a homogeneous or heterogeneous mixture?

33. Can an aqueous solution of table salt be turned into a heterogeneous mixture? If possible, how to do it?

34. What mixtures can be separated by filtration: a) a mixture of sand and clay; b) a mixture of alcohol and copper filings; c) a mixture of water and gasoline; d) a mixture of water with pieces of plastic? Name the substances that will remain on the filter.

35. How would you separate the mixture of: a) table salt and chalk; b) alcohol and water? What differences in the properties of substances make it possible to use the method you have chosen?

36. Consider an experiment to separate a mixture of table salt, sand, iron and sawdust. Make a plan, briefly describe each stage of the experiment and talk about the expected results.

Experimenting at home

settling

Pour water into two glasses. Pour 1/2 teaspoon of sand into one glass, and the same amount of starch into another. Stir both mixtures at the same time. Do particles of matter settle in water at the same rate? If not, which particles settle faster and why?

Write down your observations in a notebook.

Separation of a mixture of three solids

Mix small amounts of crushed styrofoam, sand and table salt.

What methods can be used to separate this mixture?

Divide mixture 1 . If heating is necessary, use it very carefully.

Describe each step of the experiment in your notebook.

Popel P. P., Kriklya L. S., Chemistry: Pdruch. for 7 cells. zahalnosvit. navch. zakl. - K .: Exhibition Center "Academy", 2008. - 136 p.: il.

Give 5 examples of homogeneous and heterogeneous mixtures that you encounter every day. and got the best answer

Answer from Yergey Meshalkin[active]
A homogeneous mixture is a mixture where the substances are in the same phase, they are also called homogeneous.
An inhomogeneous mixture is a mixture where the substances are in different phases. e.g. solid and liquid or gaseous and liquid. another name is heterovenous systems.
an example of homogeneous mixtures - a solution of sulfuric acid is a mixture of water and acid (electrolyte in a battery), a solution of sugar in tea, broth, perfume, gasoline.
an example of heterogeneous mixtures is sand in water (aquarium), soup, earth in a pot, tea leaves, indoor air (dust!).

Answer from Ekaterina Andreeva[newbie]
thanks guys

Answer from Karina afanasenko[newbie]
One : air, sweet water, salt water, alcohol + water, glass.
Not one. : oil + water, muddy water, blood (seen under a microscope), dusty air, sand.

Answer from Tim Verlov[guru]
homogeneous, though with some impurities, probably only the air that I breathe. everything else is heterogeneous, from food and water to slop and garbage 🙂

Answer from 3 answers[guru]

Hello! Here is a selection of topics with answers to your question: Give 5 examples of homogeneous and heterogeneous mixtures that you encounter every day.

February 26, 2016

Chemistry is the study of substances and their properties. When they are mixed, mixtures arise that acquire new valuable qualities.

What is a mixture

A mixture is a collection of individual substances. They are not only made by scientists in laboratories under certain conditions. Every day we start with fragrant tea or coffee, to which we add sugar. Or we cook a delicious soup, which must be salted. These are the real mixtures. We just don't think about it at all.

If it is impossible to distinguish particles of substances with the naked eye, then you have homogeneous mixtures (homogeneous). They can be obtained by dissolving the same sugar in tea or coffee.

But if you add sand to sugar, their particles can be distinguished without difficulty. Such a mixture is considered heterogeneous or heterogeneous.

In the manufacture of mixtures of this type, it is possible to use substances that are in different states of aggregation: solid or liquid. Ground pepper mixture different kind or other seasonings are most often heterogeneous dry formulations.

If any liquid is used in the process of preparing a heterogeneous product, then the resulting mass is called a suspension. And there are several types of them. When liquids are mixed with solids, suspensions are formed. Their example is a mixture of water with sand or clay. When a builder makes cement, a cook mixes flour with water, a child brushes his teeth with toothpaste, they all use slurries.

Another kind of heterogeneous mixtures can be obtained by mixing two liquids. Naturally, if their particles are distinguishable. Drop vegetable oil into water - and get an emulsion.

Homogeneous mixtures

The best known of this group of substances is air. Every student knows that it contains a number of gases: nitrogen, oxygen, carbon dioxide, water vapor and impurities. Can they be seen and seen with the naked eye? Of course not.

Thus, both air and sweet water are homogeneous mixtures. They can be in different aggregate states. But most often liquid homogeneous mixtures are used. They consist of a solvent and a solute. Moreover, the first component is either liquid or taken in a larger volume.

Substances cannot dissolve in infinite quantities. For example, only two kilograms of sugar can be added to a liter of water. Further, this process simply will not occur. This solution will become saturated.

An interesting phenomenon is represented by solid homogeneous mixtures. So, hydrogen is easily distributed in various metals. The intensity of the dissolution process depends on many factors. It increases with an increase in the temperature of the liquid and air, with the grinding of substances and as a result of their mixing.

Surprising is the fact that absolutely insoluble substances do not exist in nature. Even silver ions are distributed between water molecules, forming a homogeneous mixture. Such solutions are widely used in everyday life and human life. For example, everyone's favorite and healthy milk is a homogeneous mixture.

Methods for separating mixtures

Sometimes it becomes necessary not only to obtain homogeneous solutions, but also to separate homogeneous mixtures. Let's say there is only salt water in the house, but you need to get its crystals separately. To do this, a similar mass is evaporated. Homogeneous mixtures, examples of which were given above, are most often separated in this way.

Distillation is based on differences in boiling point. Everyone knows that water begins to evaporate at 100 degrees Celsius, and ethyl alcohol - at 78. A mixture of these liquids is heated. First, the alcohol vapor evaporates. They are condensed, that is, they are transferred to a liquid state, in contact with any cooled surface.

Using a magnet, mixtures containing metals are separated. For example, iron and wood chips. Vegetable oil and water can be separately obtained by settling.

Heterogeneous and homogeneous mixtures, examples of which are illustrated in the article, are of great economic importance. Minerals, air, groundwater, seas, food products, building materials, drinks, pastes - all this is a combination of individual substances, without which life would be simply impossible.

Source: fb.ru

Actual

Miscellaneous
Miscellaneous

Every substance contains impurities. A substance is considered pure if it contains almost no impurities.

Mixtures of substances are either homogeneous or heterogeneous. In a homogeneous mixture, the components cannot be detected by observation, but in an inhomogeneous mixture it is possible.

Some physical properties of a homogeneous mixture differ from those of the components.

In a heterogeneous mixture, the properties of the components are preserved.

Inhomogeneous mixtures of substances are separated by settling, filtering, sometimes by the action of a magnet, and homogeneous mixtures are separated by evaporation and distillation (distillation).

Pure substances and mixtures

We live among chemical substances. We inhale air, and this is a mixture of gases (nitrogen, oxygen and others), we exhale carbon dioxide. We wash ourselves with water - this is another substance, the most common on Earth. We drink milk - a mixture of water with the smallest droplets of milk fat, and not only: there is also milk protein casein, mineral salts, vitamins and even sugar, but not the one with which they drink tea, but a special milk - lactose. We eat apples, which consist of a whole range of chemicals - sugar, malic acid, vitamins... apple, but also any other food. We not only live among chemicals, but we ourselves are made of them. Every person - his skin, muscles, blood, teeth, bones, hair are built of chemicals, like a house of bricks. Nitrogen, oxygen, sugar, vitamins are substances of natural, natural origin. Glass, rubber, steel are also substances, more precisely, materials (mixtures of substances). Both glass and rubber are of artificial origin; they did not exist in nature. Completely pure substances are not found in nature or are very rare.

Each substance always contains a certain amount of impurities. A substance that contains almost no impurities is called pure. They work with such substances in a scientific laboratory, a school chemistry room. Note that absolutely pure substances do not exist.

An individual pure substance has a certain set of characteristic properties (constant physical properties). Only pure distilled water has tmelt = 0 °С, tboil = 100 °С, and has no taste. Sea water freezes at a lower temperature, and boils at a higher temperature, its taste is bitter-salty. The water of the Black Sea freezes at a lower temperature and boils at a higher temperature than the water of the Baltic Sea. Why? The point is that in sea ​​water contains other substances, such as dissolved salts, i.e. it is a mixture various substances, the composition of which varies over a wide range, while the properties of the mixture are not constant. The concept of "mixture" was defined in the 17th century. English scientist Robert Boyle: "A mixture - complete system consisting of dissimilar components.

Almost all natural substances, food products (except salt, sugar, and some others), many medicinal and cosmetic products, household chemicals, and building materials are mixtures.

Comparative characteristics of a mixture and a pure substance

Each substance contained in a mixture is called a component.

Classification of mixtures

There are homogeneous and heterogeneous mixtures.

Homogeneous mixtures (homogeneous)

Add a small portion of sugar to a glass of water and stir until all the sugar is dissolved. The liquid will taste sweet. Thus, the sugar did not disappear, but remained in the mixture. Ho, we will not see its crystals, even when examining a drop of liquid in a powerful microscope. The prepared mixture of sugar and water is homogeneous; the smallest particles of these substances are evenly mixed in it.

Mixtures in which components cannot be detected by observation are called homogeneous.

Most metal alloys are also homogeneous mixtures. For example, an alloy of gold and copper (used to make jewelry) lacks red copper particles and yellow gold particles.

From materials that are homogeneous mixtures of substances, many items for various purposes are made.

All mixtures of gases, including air, belong to homogeneous mixtures. There are many homogeneous mixtures of liquids.

Homogeneous mixtures are also called solutions, even if they are solid or gaseous.

Let us give examples of solutions (air in a flask, table salt + water, small change: aluminum + copper or nickel + copper).

Heterogeneous mixtures (heterogeneous)

You know that chalk does not dissolve in water. If its powder is poured into a glass of water, then chalk particles can always be found in the resulting mixture, which are visible to the naked eye or through a microscope.

Mixtures in which components can be detected by observation are called heterogeneous.

Heterogeneous mixtures include most minerals, soil, building materials, living tissues, turbid water, milk and other foods, some drugs and cosmetics.

In a heterogeneous mixture, the physical properties of the components are preserved. So, iron filings mixed with copper or aluminum do not lose their ability to be attracted to a magnet.

Some types of heterogeneous mixtures have special names: foam (for example, foam, soap suds), suspension (a mixture of water with a small amount of flour), emulsion (milk, well-shaken vegetable oil with water), aerosol (smoke, fog).

Methods for separating mixtures

In nature, substances exist in the form of mixtures. For laboratory research, industrial productions, for the needs of pharmacology and medicine, pure substances are needed.

There are many methods for separating mixtures. They are chosen taking into account the type of mixture, state of aggregation and differences in the physical properties of the components.

Methods for separating mixtures

These methods are based on differences in the physical properties of the components of the mixture.

Consider methods for separating heterogeneous and homogeneous mixtures.

Blend example	Separation method
Suspension - a mixture of river sand with water	settling Separation by settling is based on different densities of the substances. Heavier sand settles to the bottom. You can also separate the emulsion: to separate oil or vegetable oil from water. In the laboratory, this can be done using a separating funnel. Oil or vegetable oil forms the top, lighter layer. As a result of settling, dew falls out of the fog, soot is deposited from smoke, cream is settled in milk.
A mixture of sand and table salt in water	Filtration The separation of heterogeneous mixtures by filtration is based on the different solubility of substances in water and on various sizes particles. Only particles of substances commensurate with them pass through the pores of the filter, while larger particles are retained on the filter. So you can separate a heterogeneous mixture of table salt and river sand. Various porous substances can be used as filters: cotton wool, coal, fired clay, pressed glass, and others. The filtering method is the basis for the operation of household appliances, such as vacuum cleaners. It is used by surgeons - gauze bandages; drillers and workers of elevators - respiratory masks. With the help of a tea strainer for filtering tea leaves, Ostap Bender - the hero of the work of Ilf and Petrov - managed to take one of the chairs from Ellochka Ogre ("The Twelve Chairs").
A mixture of iron powder and sulfur	Action by magnet or water Iron powder was attracted by a magnet, but sulfur powder was not. The non-wettable sulfur powder floated to the surface of the water, while the heavy wettable iron powder settled to the bottom.
A solution of salt in water is a homogeneous mixture	Evaporation or crystallization The water evaporates and salt crystals remain in the porcelain cup. When water is evaporated from lakes Elton and Baskunchak, table salt is obtained. This separation method is based on the difference in the boiling points of the solvent and the solute. If a substance, such as sugar, decomposes when heated, then the water is not completely evaporated - the solution is evaporated, and then sugar crystals are precipitated from a saturated solution. Sometimes it is required to remove impurities from solvents with a lower boiling point, for example, water from salt. In this case, the vapors of the substance must be collected and then condensed upon cooling. This method of separating a homogeneous mixture is called distillation, or distillation. IN special devices- distillers receive distilled water, which is used for the needs of pharmacology, laboratories, car cooling systems. At home, you can design such a distiller. If, however, a mixture of alcohol and water is separated, then the first to be distilled off (collected in a receiving test tube) is alcohol with tboil = 78 °C, and water will remain in the test tube. Distillation is used to obtain gasoline, kerosene, gas oil from oil.

Chromatography is a special method for separating components based on their different absorption by a certain substance.

If you hang a strip of filter paper over a vessel with red ink, immersing only the end of the strip in them. The solution is absorbed by the paper and rises along it. But the border of the rise of the paint lags behind the border of the rise of the water. This is how the separation of two substances occurs: water and the coloring matter in the ink.

With the help of chromatography, the Russian botanist M. S. Tsvet was the first to isolate chlorophyll from the green parts of plants. In industry and laboratories, instead of filter paper for chromatography, starch, coal, limestone, and aluminum oxide are used. Are substances always required with the same degree of purification?

For different purposes, substances with different degrees of purification are needed. Cooking water is sufficiently settled to remove impurities and chlorine used to disinfect it. Drinking water must first be boiled. And in chemical laboratories for the preparation of solutions and experiments, in medicine, distilled water is needed, as purified as possible from the substances dissolved in it. Highly pure substances, the content of impurities in which does not exceed one millionth of a percent, are used in electronics, semiconductor, nuclear technology and other precision industries.