Does oxygen have thermal and electrical conductivity? Water: electrical conductivity and thermal conductivity

The purpose of the lesson. Concretize knowledge about a chemical element and a simple substance. To study the physical properties of oxygen. To form ideas about the methods of obtaining and collecting oxygen in the laboratory.

Tasks:

Educational:
– Be able to distinguish between the concepts of “chemical element” and “simple substance”
using oxygen as an example.
– Be able to characterize the physical properties of oxygen and methods
collecting oxygen.
– Be able to arrange the coefficients in the reaction equations.
Educational:
the formation of accuracy in the performance of laboratory experiments;
care, respect.
Developing:
– Formation of building logical chains, own chemical
terminology, cognitive activity, inferences and judgments.

Basic concepts. Chemical element, simple substance, physical properties, catalysts.

Planned learning outcomes. To be able to distinguish between the concepts of “chemical element” and “simple substance” using oxygen as an example. To be able to characterize the physical properties of oxygen and the methods of collecting oxygen. Be able to arrange the coefficients in the reaction equations.

Experience: Obtaining oxygen from hydrogen peroxide and confirming its presence.

Demos. Obtaining oxygen from potassium permanganate. Collection of oxygen by the method of displacement of air and confirmation of its presence.

Equipment and reagents: D.I. Mendeleev’s table, handout (test), a device for producing oxygen from potassium permangate (a conical flask with a rubber stopper, a gas outlet tube, PH-12, a tripod, a foot, cotton wool), hydrogen peroxide 20 ml (15 bottles), manganese oxide (IV) (15 bottles), dosing spoon (15 pcs.), alcohol lamp (15 pcs.), matches (15 pcs.), splinter (15 pcs.), potassium permanganate (5 g).

Lesson type: A lesson in learning new knowledge.

Teaching methods:

Explanatory-illustrative (verbal: conversation, presentation; verbal-visual: independent work of students with visual aids; verbal-visual-practical: work of students with handouts, performing chemical experiments, performing written independent work).
Partial search (heuristic) method (verbal: conversation-discussion; verbal-visual: discussion with a demonstration of visual aids, independent work of students with a visual aid; verbal-visual-practical: work of students with handouts, performing a chemical experiment, performing a written independent work).
Research method (verbal-visual-practical: performing a research chemical experiment).

Forms of organization of activity: frontal, group (steam).

I. Organizational stage.

Greetings.
Definition of absent.
Check readiness for the lesson.

The presence of a diary, a class notebook, a textbook on chemistry, a pen.

II. Preparing students for active and conscious assimilation of new material.

Teacher: In order to determine the topic of today's lesson, you and I need to solve a rebus?

slide 1

Solve the puzzle and we will find out the topic of today's lesson.

Rice. 1

(BRUSHES) KI + (ELEPHANT) SLO + ROD

OXYGEN

Teacher: The topic of today's lesson: “Oxygen, its general characteristics and presence in nature. Physical properties of oxygen. Receipt".

slide 2

The topic of today's lesson: “Oxygen, its general characteristics and presence in nature. Physical properties of oxygen. Receipt".

slide 3

“Oxygen” is the substance around which Earth's chemistry revolves.

J. Berzelius

Teacher: Using the language of chemistry, it is necessary to write on the board: oxygen as a chemical element and as a simple substance.

Oxygen - as an element - O.

Oxygen - as a simple substance - O 2.

Teacher: Now several phrases (sayings) will appear on the screen, you need to determine in what meaning oxygen is mentioned in them - as a chemical element or as a simple substance.

slide 4

Exercise: Define oxygen as a chemical element or simple substance.

Oxygen is a part of vital organic substances: proteins, fats, carbohydrates.
All living things on Earth breathe oxygen.
Rust contains iron and oxygen.
Fish breathe oxygen dissolved in water.
During photosynthesis, green plants release oxygen.

Teacher: You need with the help of PSHE them. D.I. Mendeleev to characterize the chemical element “Oxygen”, according to the following plan:

Slide 5:

Serial number -
Relative atomic mass -
Period -
Group -
Subgroup -
Valency -

Teacher: Let's check the attention to the screen

slide 6

Ordinal number - 8
Relative atomic mass - Ar (O) = 16
Period - second
Group - VI
Subgroup - a (main)
Valence - II

Slide 7

Distribution of oxygen in nature:

First place in terms of prevalence in the earth's crust, i.e. lithosphere, occupies oxygen - 49%, followed by silicon - 26%, aluminum - 7%, iron - 5%, calcium - 4%, sodium - 2%, potassium - 2%, magnesium - 2%, hydrogen - 1%.

IN biosphere About 65% of the mass of living organisms is oxygen.

IN hydrosphere it accounts for 89%.

IN atmosphere: 23% by weight, 21% by volume.

Rice. 2

Teacher: You need with the help of PSHE them. D.I. Mendeleev to characterize the simple substance “Oxygen”.

So, what is the chemical formula of a simple substance - 0 2

Relative molecular weight Mg (0 2) = 32

Slide 8

History of the discovery of oxygen.

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Figure 5

Rice. 4

Rice. 6

The teacher comments: In 1750 M.V. Lomonosov conducted experiments and proved that the air contains a substance that oxidizes the metal. He called him phlogiston.

Received oxygen in 1771 Karl Scheele. Regardless of him, oxygen was obtained by J. Priestley in 1774.

And the story is simple...
Joseph Priestley once
Mercury oxide heating,
Found a strange gas.
Gas without color, without name,
The candle burns brighter.
Isn't it bad for breathing?
You won't find out from a doctor!
New gas came out of the flask -
Nobody knows him.
Mice breathe this gas
Under a glass cover.
A person breathes it too ...

In 1775, A. Lavoisier established that oxygen is an integral part of air and is contained in many substances.

Nature created the world from atoms:
Two atoms of the lungs took hydrogen,
Added an atom of oxygen -
And it turned out a particle of water,
Sea of water, oceans and ice…
Became oxygen
Almost everywhere stuffing.
With silicon, he turned into a grain of sand.
Oxygen got into the air
Surprisingly,
From the blue depths of the ocean.
And plants appeared on the Earth.
Life appeared:
Breathing, burning...
The first birds and the first beasts
The first people to live in a cave...
Fire was made by friction
Although they did not know the cause of the fire.
The role of oxygen on our Earth
The great Lavoisier understood.

Teacher: Now let's get acquainted with oxygen by experience. Since we will use a heating device (alcohol lamp), it is necessary to remember TB when working with an alcohol lamp:

When using a spirit lamp, it is impossible to light it from another spirit lamp, as alcohol may spill and a fire will occur.
To extinguish the flame of the spirit lamp, it should be closed with a cap.

Pour H 2 O 2 (hydrogen peroxide) solution into a beaker.

Light the spirit lamp, bring the torch to the flame and put out the torch. Then add manganese (IV) oxide to a beaker and bring a smoldering torch to the beaker - what is observed?

Student: Luchina - flashes. In this way, we determined that there is oxygen in the beaker.

Teacher: In this experiment, manganese (IV) oxide is a catalyst - a substance that accelerates the process of a chemical reaction, but is not itself consumed.

Demo experiment:"Production of oxygen from potassium permanganate".

We collect the device.

We collect oxygen by displacing air into a conical flask, after a while we check for the presence of oxygen, using a smoldering torch, if it flares up, then a sufficient amount of oxygen has been collected.

We close with a rubber stopper and put it on a lifting table.

And we invite students to characterize the physical properties of oxygen according to the following criteria.

Slide 9

State of aggregation -...
Color - ...
Smell - ...
Solubility in water...
t o kip. –...
Electrical conductivity is...
Thermal conductivity is...
Heavier or lighter than air

Teacher: Let's check the attention to the screen.

Slide 10

Aggregate state - gas.
Color - no color
Smell - odorless
Solubility in water - poorly soluble
t° b.p. - 183°С
Electrical conductivity - non-conductive
Thermal conductivity - conducts heat poorly (poor)
Heavier than air

Teacher: We pose a problematic question to the students: Why is oxygen in the picture in the form of a blue liquid?

slide 11

Rice. 7

Students answer (teacher adds): This oxygen is in a liquefied state, and liquid oxygen is blue.

Now let's summarize and write down in a notebook the different ways of obtaining oxygen that we observed today.
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Rice. 9

Teacher: At the end of the lesson, we will test our knowledge.

Who knows the formula of water since school days? Of course, everything. It is likely that from the entire course of chemistry, for many who then do not study it specializedly, only the knowledge of what the formula H 2 O stands for is left. But now we will try to understand in as much detail and depth as possible what are its main properties and why life without it on planet Earth is not possible.

Water as a substance

The water molecule, as we know, consists of one oxygen atom and two hydrogen atoms. Its formula is written as follows: H 2 O. This substance can have three states: solid - in the form of ice, gaseous - in the form of steam, and liquid - as a substance without color, taste and smell. By the way, this is the only substance on the planet that can exist in all three states simultaneously in natural conditions. For example: at the poles of the Earth - ice, in the oceans - water, and evaporation under the sun's rays is steam. In this sense, water is anomalous.

Water is also the most common substance on our planet. It covers the surface of planet Earth by almost seventy percent - these are oceans, and numerous rivers with lakes, and glaciers. Most of the water on the planet is salty. It is unsuitable for drinking and for farming. Fresh water makes up only two and a half percent of the total amount of water on the planet.

Water is a very strong and high-quality solvent. Due to this, chemical reactions in water take place at a tremendous speed. This same property affects the metabolism in the human body. that the body of an adult is seventy percent water. In a child, this percentage is even higher. By old age, this figure drops from seventy to sixty percent. By the way, this feature of water clearly demonstrates that it is the basis of human life. The more water in the body - the healthier, more active and younger it is. Therefore, scientists and doctors of all countries tirelessly repeat that you need to drink a lot. It is water in its pure form, and not substitutes in the form of tea, coffee or other drinks.

Water forms the climate on the planet, and this is not an exaggeration. Warm currents in the ocean heat entire continents. This is due to the fact that water absorbs a lot of solar heat, and then gives it away when it starts to cool. So it regulates the temperature on the planet. Many scientists say that the Earth would have cooled down and turned into stone long ago if it weren’t for the presence of so much water on the green planet.

Water properties

Water has many very interesting properties.

For example, water is the most mobile substance after air. From the school course, many, for sure, remember such a thing as the water cycle in nature. For example: a stream evaporates under the influence of direct sunlight, turns into water vapor. Further, this steam is carried somewhere by the wind, collects in clouds, and even falls in the mountains in the form of snow, hail or rain. Further, from the mountains, the brook again runs down, partially evaporating. And so - in a circle - the cycle is repeated millions of times.

Water also has a very high heat capacity. It is because of this that water bodies, especially oceans, cool very slowly during the transition from a warm season or time of day to a cold one. Conversely, when the air temperature rises, the water heats up very slowly. Due to this, as mentioned above, water stabilizes the air temperature throughout our planet.

After mercury, water has the highest surface tension. It is impossible not to notice that a drop accidentally spilled on a flat surface sometimes becomes an impressive speck. This shows the ductility of water. Another property manifests itself when the temperature drops to four degrees. As soon as the water cools to this mark, it becomes lighter. Therefore, ice always floats on the surface of the water and freezes in a crust, covering rivers and lakes. Thanks to this, in ponds that freeze in winter, fish do not freeze out.

Water as a conductor of electricity

First, you should learn about what electrical conductivity is (including water). Electrical conductivity is the ability of a substance to conduct an electric current through itself. Accordingly, the electrical conductivity of water is the ability of water to conduct current. This ability directly depends on the amount of salts and other impurities in the liquid. For example, the electrical conductivity of distilled water is almost minimized due to the fact that such water is purified from various additives that are so necessary for good electrical conductivity. An excellent current conductor is sea water, where the concentration of salts is very high. The electrical conductivity also depends on the temperature of the water. The higher the temperature, the greater the electrical conductivity of water. This regularity was revealed thanks to multiple experiments of physicists.

Water conductivity measurement

There is such a term - conductometry. This is the name of one of the methods of electrochemical analysis based on the electrical conductivity of solutions. This method is used to determine the concentration in solutions of salts or acids, as well as to control the composition of some industrial solutions. Water has amphoteric properties. That is, depending on the conditions, it is able to exhibit both acidic and basic properties - to act both as an acid and as a base.

The instrument used for this analysis has a very similar name - a conductometer. Using a conductometer, the electrical conductivity of electrolytes in a solution is measured, the analysis of which is being carried out. Perhaps it is worth explaining another term - electrolyte. This is a substance that, when dissolved or melted, decomposes into ions, due to which an electric current is subsequently conducted. An ion is an electrically charged particle. Actually, the conductometer, taking as a basis certain units of electrical conductivity of water, determines its electrical conductivity. That is, it determines the electrical conductivity of a specific volume of water, taken as the initial unit.

Even before the beginning of the seventies of the last century, the unit of measure "mo" was used to indicate the conductivity of electricity, it was a derivative of another quantity - Ohm, which is the main unit of resistance. Electrical conductivity is a quantity that is inversely proportional to resistance. Now it is measured in Siemens. This value got its name in honor of the physicist from Germany - Werner von Siemens.

Siemens

Siemens (it can be denoted by both Cm and S) is the reciprocal of Ohm, which is a unit of measurement of electrical conductivity. One cm is equal to any conductor whose resistance is 1 ohm. Siemens is expressed through the formula:

1 Sm \u003d 1: Ohm \u003d A: B \u003d kg −1 m −2 s³A², where
A - ampere,
V - volt.

Thermal conductivity of water

Now let's talk about - this is the ability of a substance to transfer thermal energy. The essence of the phenomenon lies in the fact that the kinetic energy of atoms and molecules, which determine the temperature of a given body or substance, is transferred to another body or substance during their interaction. In other words, thermal conductivity is heat exchange between bodies, substances, as well as between a body and a substance.

The thermal conductivity of water is also very high. People daily use this property of water without noticing it. For example, pouring cold water into a container and cooling drinks or foods in it. Cold water takes heat from the bottle, container, giving away cold in return, and the reverse reaction is also possible.

Now the same phenomenon can be easily imagined on a planetary scale. The ocean heats up during the summer, and then - with the onset of cold weather, it slowly cools down and gives up its heat to the air, thereby heating the continents. Having cooled down during the winter, the ocean begins to warm up very slowly compared to the land and gives up its coolness to the continents languishing from the summer sun.

Density of water

It was said above that fish live in a reservoir in winter due to the fact that water freezes with a crust over their entire surface. We know that water begins to turn into ice at a temperature of zero degrees. Due to the fact that the density of water is greater than the density floats and freezes on the surface.

water properties

Also, water under different conditions can be both an oxidizing agent and a reducing agent. That is, water, giving up its electrons, is positively charged and oxidized. Or it acquires electrons and is charged negatively, which means it is restored. In the first case, the water oxidizes and is called dead. It has very powerful bactericidal properties, but you don’t need to drink it. In the second case, the water is alive. It invigorates, stimulates the body to recover, brings energy to the cells. The difference between these two properties of water is expressed in the term "redox potential".

What can water react with?

Water is able to react with almost all substances that exist on Earth. The only thing is that for the occurrence of these reactions, it is necessary to provide a suitable temperature and microclimate.

For example, at room temperature, water reacts well with metals such as sodium, potassium, barium - they are called active. Halogens are fluorine and chlorine. When heated, water reacts well with iron, magnesium, coal, methane.

With the help of various catalysts, water reacts with amides, esters of carboxylic acids. A catalyst is a substance that seems to push the components to a mutual reaction, accelerating it.

Is there water anywhere else but Earth?

So far, water has not been found on any planet in the solar system, except for the Earth. Yes, they assume its presence on the satellites of such giant planets as Jupiter, Saturn, Neptune and Uranus, but so far scientists do not have exact data. There is another hypothesis, not yet fully verified, about groundwater on the planet Mars and on the Earth's satellite - the Moon. Regarding Mars, a number of theories have been put forward that once there was an ocean on this planet, and its possible model was even designed by scientists.

Outside the solar system, there are many large and small planets, where, according to scientists, there may be water. But so far there is not the slightest way to be sure of this for sure.

How to use the thermal and electrical conductivity of water for practical purposes

Due to the fact that water has a high heat capacity, it is used in heating mains as a heat carrier. It provides heat transfer from the producer to the consumer. Many nuclear power plants also use water as an excellent coolant.

In medicine, ice is used for cooling, and steam for disinfection. Ice is also used in the catering system.

In many nuclear reactors, water is used as a moderator for the success of a nuclear chain reaction.

Pressurized water is used to split, break through and even cut rocks. This is actively used in the construction of tunnels, underground facilities, warehouses, subways.

Conclusion

It follows from the article that water, in terms of its properties and functions, is the most irreplaceable and amazing substance on Earth. Does the life of a person or any other living being on Earth depend on water? Certainly yes. Does this substance contribute to human scientific activity? Yes. Does water have electrical conductivity, thermal conductivity and other useful properties? The answer is also yes. Another thing is that there is less and less water on Earth, and even more so clean water. And our task is to preserve and protect it (and, therefore, all of us) from extinction.

Density, heat capacity, properties of oxygen O 2

The table presents the thermophysical properties of oxygen such as density, enthalpy, entropy, specific heat, dynamic viscosity, thermal conductivity. The properties in the table are given for gaseous oxygen at atmospheric pressure, depending on the temperature in the range from 100 to 1300 K.

The density of oxygen is 1.329 kg / m 3 at room temperature. When oxygen is heated, its density decreases. The thermal conductivity of oxygen is 0.0258 W / (m deg) at room temperature and increases with increasing temperature of this gas.

Specific heat capacity of oxygen at room temperature is 919 J/(kg deg). The heat capacity of oxygen increases with an increase in its temperature. Also, when oxygen is heated, the values of its properties such as enthalpy, entropy, and viscosity increase.

Note: be careful! The thermal conductivity in the table is given to the power of 10 2 . Don't forget to divide by 100.

Thermal conductivity of oxygen in liquid and gaseous states

The table shows the values of the thermal conductivity of oxygen in liquid and gaseous states at various temperatures and pressures. Thermal conductivity is indicated in the temperature range from 80 to 1400 K and pressure from 1 to 600 atm.

The thermal conductivity values in the table above the line refer to liquid oxygen, and below it to gaseous oxygen. According to the table, it can be seen that the thermal conductivity of liquid oxygen is higher than that of gaseous oxygen and increases with increasing pressure.

Unit W/(m deg).

Thermal conductivity of oxygen at high temperatures

The table gives the values of the thermal conductivity of oxygen at high temperatures (from 1600 to 6000 K) and pressures from 0.001 to 100 atm.

At temperatures above 1300°C, oxygen begins to dissociate, and at a certain pressure, its thermal conductivity reaches its maximum values. According to the table, it can be seen that the thermal conductivity of dissociated oxygen at high temperatures can reach values up to 3.73 W/(m deg).

Note: Be careful! The thermal conductivity in the table is given to the power of 10 3 . Don't forget to divide by 1000.

Thermal conductivity of liquid oxygen at the saturation line

The table shows the values of the thermal conductivity of liquid oxygen at the saturation line. The thermal conductivity is given in the temperature range from 90 to 150 K. It should be noted that the thermal conductivity of liquid oxygen decreases with increasing temperature.

Note: Be careful! The thermal conductivity in the table is given to the power of 10 3 . Don't forget to divide by 1000.

Sources:
1.
2. .

You begin to get acquainted with a new subject - chemistry. What does chemistry study?

As you know from the course of physics, many substances are made up of molecules, and molecules are made up of atoms. Atoms are so small that many billions of them can fit on the point of a needle. Nevertheless, only 114 types of atoms are distinguished.

Substances such as neon, argon, krypton, and helium are composed of individual isolated atoms. They are also called noble or inert gases, because their atoms do not combine with each other and hardly combine with atoms of other chemical elements. Hydrogen atoms are quite another matter. They can exist singly (Fig. 4, a), as in the Sun, which consists of more than half of individual hydrogen atoms. Two atoms can combine into molecules (Fig. 4, b), forming molecules of the lightest gas, which, like a chemical element, is called hydrogen. Hydrogen atoms can also combine with atoms of other chemical elements. For example, two hydrogen atoms, connecting with one oxygen atom (Fig. 4, c), form molecules of a well-known substance - water.

Rice. 4.
Forms of existence of the chemical element hydrogen:
a - hydrogen atoms; b - hydrogen molecules; c - hydrogen atoms in a water molecule

Similarly, the concept of "chemical element oxygen" combines isolated oxygen atoms, oxygen - a simple substance, the molecules of which consist of two oxygen atoms, and oxygen atoms that are part of complex substances. So, the composition of carbon dioxide molecules includes atoms of oxygen and carbon, the composition of sugar molecules - atoms of carbon, hydrogen and oxygen.

Therefore, each chemical element exists in three forms: free atoms, simple substances and complex substances (see Fig. 4).

The concept of "chemical element" is broader, and should not be confused with the concept of "simple substance", especially if their names coincide. For example, when they say that water contains hydrogen, they mean a chemical element, and when they say that hydrogen is an environmentally friendly type of fuel, they mean a simple substance.

Different substances differ from each other in their properties. So, hydrogen is a gas, very light, colorless, odorless, tasteless, has a density of 0.00009 g / cm 3, boils at a temperature of -253 ° C, and melts at a temperature of -259 ° C, etc. These properties substances are called physical.

You can describe the physical properties of a substance using the following plan:

In what state of aggregation (gaseous, liquid, solid) is the substance under these conditions?
What color is the substance? Does it have shine?
Does the substance have an odor?
What is the hardness of a substance according to the relative hardness scale (Mohs scale) (Fig. 5)? (See reference books.)

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Hardness scale

Does the substance exhibit plasticity, fragility, elasticity?
Does the substance dissolve in water?
What is the melting point and boiling point of the substance? (See reference books.)
What is the density of matter? (See reference books.)
Does a substance have thermal and electrical conductivity? (See reference books.)

Lab Experience #1
Comparison of the properties of solid crystalline substances and solutions

Compare using the one on p. 10 plan, the properties of the samples of substances given to you in cups:

option 1 - crystalline sugar and table salt;
option 2 - glucose and citric acid.

Knowing the properties of substances, a person can use them with greater benefit for himself. For example, consider the properties and applications of aluminum (Figure 6).

Rice. 6.
Application of aluminum:
1 - aircraft construction; 2 - rocket science; 3 - production of power lines; 4 - production of tableware, cutlery and packaging foil

Due to its lightness and strength, aluminum and its alloys are used in aircraft and rocket manufacturing; it is not for nothing that aluminum is called the “winged metal”.

The lightness and good electrical conductivity of aluminum is used in the manufacture of electrical wires for power lines (TL).

Thermal conductivity and non-toxicity are important in the manufacture of aluminum cookware.

Non-toxicity and plasticity make it possible to widely use thin sheets of aluminum - foil - as a packaging material for chocolate bars, tea, margarine, milk, juices, and other products, as well as for medicines placed in contour cells.

The introduction of aluminum alloys in construction increases the durability and reliability of structures.

These examples illustrate that different physical bodies can be made from one substance - material (aluminum).

Aluminum is able to burn with a dazzling flame (Fig. 7), so it is used in colorful fireworks and in the manufacture of sparklers (remember N. Nosov's story "Bengal Lights"). During combustion, aluminum turns into another substance - aluminum oxide.

Rice. 7.
Burning aluminum - the basis of sparklers and fireworks

Keywords and phrases

The subject of chemistry.
Substances are simple and complex.
Properties of substances.
A chemical element and forms of its existence: free atoms, simple substances and complex substances, or compounds.

Work with computer

Refer to the electronic application. Study the material of the lesson and complete the suggested tasks.
Search the Internet for email addresses that can serve as additional sources that reveal the content of the keywords and phrases of the paragraph. Offer the teacher your help in preparing a new lesson - make a report on the key words and phrases of the next paragraph.

Questions and tasks

Phileo (Greek) means "I love", phobos - "I'm afraid." Give an explanation of the terms "chemophilia" and "chemophobia", reflecting the sharply opposite attitude of groups of people towards chemistry. Which of them is right? Justify your point of view.
A mandatory attribute of an infinite number of espionage and other detective works is potassium cyanide, more precisely, potassium cyanide, which has the property of paralyzing the nervous system, thereby leading the victim to instant death. Give examples of the properties of other substances that are used in literary works.
Write down separately the names of substances and the names of bodies from the list below: copper, coin, glass, glass, vase, ceramics, wire, aluminum. Use the hint: to the name of the body - a noun - you can pick up a relative adjective formed from the name of the substance, for example: iron and nail - iron nail.
Write out quality adjectives: light, round, long, heavy, hard, odorous, soluble, weighty, concave, soft, liquid, transparent - which can be attributed to: a) substances; b) to bodies; c) both bodies and substances.
Compare the concepts of "simple substance" and "complex substance". Find similarities and differences.
Determine which of the substances whose molecular models are shown in Figure 2 are: a) simple substances; b) to complex substances.
Which concept is broader - "chemical element" or "simple substance"? Give a demonstrative answer.
Indicate where oxygen is spoken of as a chemical element, and where - as a simple substance:
a) oxygen is slightly soluble in water;
b) water molecules consist of two hydrogen atoms and one oxygen atom;
c) the air contains 21% oxygen (by volume);
d) oxygen is part of carbon dioxide.
Indicate where hydrogen is referred to as a simple substance, and where as a chemical element:
a) hydrogen is part of most organic compounds;
b) hydrogen is the lightest gas;
c) balloons are filled with hydrogen;
d) a methane molecule contains four hydrogen atoms.
Consider the relationship between the properties of a substance and its application on the example of: a) glass; b) polyethylene; c) sugar; d) iron.

chemically simple substance with luster, malleability, thermal and electrical conductivity

Alternative descriptions

Malleable substance with high electrical and thermal conductivity

A chemically simple substance with luster, malleability, thermal and electrical conductivity

One of the 5 elements in Chinese beliefs

. "People die for..." (Mephistopheles)

. "People die for..." (aria)

. "durable material" that may lie in the voice

1 of 5 elements in Chinese beliefs

Substance with good ductility, thermal and electrical conductivity

Precious...

Iron music group "Aerosmith"

A victim of corrosion

Both copper and gold

And copper, and sodium, and mercury

And copper and tin and iron and gold

Ductile electrically conductive substance

People die for him

Copper or titanium

Metal m. lat. crusher; and in a small form, in smelting: kinglet. everyday life, valuable, expensive metals: gold, platinum, silver; simple: iron, copper, zinc, tin, lead; chemistry has discovered such beginnings of almost all fossils, consisting of oxides and salts of krustsevy; in total, in this sense, there are more than forty metals. Metallic, -personal, -personal, pertaining to it. Metal mirror. - shine, ringing. Metal, made of crusher, made of metal. Metalloid m. semimetal, fossil beginnings, similar to metals, but without some of their properties: brilliance, ductility, heat conduction. Sulfur, phosphorus, borax are classified as metalloids. -idny, -idovy, relating to him. Metalish, metal-like, similar to a crusher. -bearing layer, ore-bearing, mine, -smooth, -smelting, relating to the melting of the crusher. - carved, - saw, related. for cutting metals. - shaving, - planing, to shavings, planing them related. Metallurgy part of mining and chemistry: the science of mining, refining and processing metals. -gichny, -chesky, related to science, art. Metallurgist m. who is engaged in this science. Metallography, description of metals

sodium or iron

Nickel - colored...

simple substance

Mercury as a chemical

Mercury, iron

Titanium, gold, aluminum or copper

chemically simple substance

A chemically simple substance with a special luster, good thermal and electrical conductivity

Chemical status of copper and iron

Black, colorful and noble

What is copper

What is mercury

What attracts a magnet

This word comes from the Greek, meaning "mine, mine"