Kipp apparatus used to produce hydrogen, carbon dioxide and hydrogen sulfide. The solid reagent is placed in the middle spherical reservoir of the apparatus on a plastic annular liner that prevents the solid reagent from entering the lower reservoir. As a solid reagent for producing hydrogen, zinc granules are used, carbon dioxide - pieces of marble, hydrogen sulfide - pieces of iron sulfide. The poured solid pieces should be about 1 cm 3. It is not recommended to use powder, as the gas current will be very strong. After loading the solid reagent into the apparatus, a liquid reagent is poured into the apparatus through the upper throat (for example, a dilute solution of hydrochloric acid in the production of hydrogen, carbon dioxide and hydrogen sulfide). The liquid is poured in such an amount that its level (with the gas valve open) reaches half of the upper spherical expansion of the lower part. Gas is passed for 5-10 minutes in order to displace air from the apparatus, after which the gas valve is closed, a safety funnel is inserted into the upper throat. The gas outlet tube is connected to the device where the gas needs to be passed.
When the valve is closed, the released gas displaces the liquid from the spherical expansion of the apparatus, and it stops working. When the tap is opened, the acid again enters the tank with the solid reagent, and the apparatus starts to work. It is one of the most convenient and safest methods for producing gases in the laboratory.
Collect gas into a vessel can different methods... The two most common methods are the water displacement method and the air displacement method. The choice of method is dictated by the properties of the gas to be collected.
Air displacement method... Almost any gas can be collected using this method. Before sampling gas, it is necessary to determine whether it is lighter than air or heavier. If the relative density of the gas in the air is greater than unity, then the receiving vessel should be held with the opening upward, since the gas is heavier than air and will sink to the bottom of the vessel (for example, carbon dioxide, hydrogen sulfide, oxygen, chlorine, etc.). If the relative density of the gas in the air is less than unity, then the receiving vessel should be held with the opening downward, since the gas is lighter than air and will rise up the vessel (for example, hydrogen, etc.). The filling of the vessel can be controlled in different ways, depending on the properties of the gas. For example, to determine oxygen, a smoldering torch is used, which, when brought to the edge of the vessel (but not inward!), Flares up; when determining carbon dioxide, the hot torch goes out.
Water displacement method... This method can only collect gases that do not dissolve in water (or slightly dissolve) and do not react with it. To collect the gas, a crystallizer is required, which is 1/3 filled with water. The receiving vessel (most often a test tube) is filled up to the top with water, closed with a finger and lowered into the crystallizer. When the opening of the vessel is under water, it is opened and a gas outlet tube is introduced into the vessel. After all the water has been forced out of the vessel by the gas, the hole is closed under water with a stopper and the vessel is removed from the crystallizer.
Checking gas for purity... Many gases burn in air. If you ignite a mixture of combustible gas with air, an explosion will occur, so the gas must be checked for purity. The test consists in burning a small portion of gas (about 15 ml) in a test tube. To do this, the gas is collected in a test tube and ignited from the flame of an alcohol lamp. If the gas does not contain air impurities, then combustion is accompanied by a light pop. If a sharp barking sound is heard, then the gas is polluted with air and needs to be cleaned.
If a dry gas outlet tube is needed for the experiment, then proceed as follows. A rubber tube with a glass tip is put on the free end of the gas outlet tube. When testing the instrument for leaks, the removable tip will get wet and the flue tube will remain dry.
Gas can be collected in a vessel using different methods. The two most common are the air displacement method and the water displacement method. Each of them has its own advantages and disadvantages, and the choice of the method is largely determined by the properties of the gas to be collected.
Air displacement method
Any gas can be collected using this method, but this raises the problem of accurately determining the moment when all the air from the receiving vessel will be displaced by the collected gas.
Before collecting gas by displacement air, you need to find out whether it is heavier or lighter than air. The position of the receiving vessel will depend on this (Fig.). To do this, calculate the relative density of the gas in air by the formula: D air. (X) = Mr (X) / 29, where Mr is the relative molecular weight of the collected gas, 29 is the relative molecular weight of air. If the calculated value turns out to be less than one, then the gas is lighter than air, and the receiving vessel must be positioned with the opening downward (Fig. 57, a). If the relative density of the gas in the air is more than unity, then the gas is heavier than air, and the receiving vessel should be positioned with the opening upward (Fig. 57, b).
Rice. 57. The position of the receptacle (1): a - for gas, which is lighter than air; b - for gas that is heavier than air.
The filling of the vessel can be controlled in different ways, depending on the type of gas being collected. For example, colored nitric oxide (IV) is easily detected by its reddish-brown color. To detect oxygen, a smoldering splinter is used, which is brought to the edge of the vessel, but not brought inside.
Water displacement method.
By using this method, it is much easier to control the filling of the receiving vessel with gas. However, this method has a serious limitation - it can not be used if the gas dissolves in water or reacts with it .
To collect gas by displacement of water, it is necessary to have a wide vessel, for example, a crystallizer, 2/3 filled with water. A receiving vessel, for example a test tube, is filled to the top with water, closed with a finger, quickly turned upside down and lowered into a crystallizer. When the opening of the test tube is under water, the opening of the test tube is opened and a gas outlet tube is introduced into the test tube (Fig. 58).
Rice. 58. A device for collecting gas by displacing water: 1 - receiving tube filled with water; 2 - crystallizer.
After all the water has been displaced from the test tube by the gas, the opening of the test tube close under water stopper and removed from the crystallizer.
If the gas that is collected by the water displacement method is obtained by heating, the following rule must be strictly observed:
Do not stop heating the tube with initial substances if the gas outlet tube is under water!
Registration of experiment results
The form of recording the results obtained during the performance of a chemical experiment is not regulated by anyone. But the protocol of the experiment must necessarily include the following points: the name of the experiment and the date of its conduct, the purpose of the experiment, a list of equipment and reagents that were used, a drawing or diagram of the device, a description of the actions that were performed during the work, observations, equations of the ongoing reactions, calculations , if they were performed while performing the work, conclusions.
The form of the report on the carried out practical work.
Record the date of the experiment and the name of the experiment.
Formulate the purpose of the experiment yourself.
Write down briefly everything you did.
Draw the experiment or draw the device that you used. Try to keep the drawing clear. Be sure to add explanatory labels to the figure. Use colored pencils or felt-tip pens to depict colored substances.
Write down your observations, i.e. describe the conditions and signs of chemical reactions.
Write the equations for all the chemical reactions that occurred during the experiment. Don't forget to place your odds.
Learn from experience (or work).
You can draw up a report on the work as a sequential description of actions and observations, or in the form of a table:
Experience no ...
|
Experience description |
Experiment drawing |
Signs of reactions |
Conclusions. Reaction equations |
When solving experimental problems related to the recognition and identification of substances, it is convenient to draw up the report in the form of another table:
|
Procedure |
Reagent |
Tube number |
Output |
||
Topic 1. Basic concepts and laws of chemistry.
Laboratory experiments.
Examples of physical phenomena.
Experiment No. 1. Heating glass (glass tube)
in the flame of an alcohol lamp.
Equipment and reagents: glass tube, spirit lamp, matches, asbestos mesh.
1. Grasp the ends of the glass tube with both hands.
2. Bring the middle of the tube into the flame of an alcohol lamp. Remember that the top of the flame is the hottest.
3. Rotate the tube, keeping the spirit lamp in the flame (fig. 59).
4. When the glass becomes very hot (after 3-4 minutes), try to bend the tube without using excessive force.
Rice. 59. Bending the glass tube.
Place the glass tube over the asbestos mesh. Be careful: hot glass on outward appearance no different from cold!
1) Has the glass changed?
2) Did you get a new substance by heating the glass tube?
Experience No. 2. Melting of paraffin.
Equipment and reagents: crucible or glass plate, spirit lamp, matches, crucible tongs or test tube holder, asbestos mesh, paraffin.
Instructions for performing the experiment.
1. Place a small piece of paraffin wax in a crucible (or on a glass plate).
2. Take the crucible (or glass plate) with crucible tongs (or fix it in the tube holder).
3. Place the wax crucible (or glass plate) on top of the spirit lamp flame. Watch the changes carefully.
4. After the paraffin has melted, place the crucible (or glass plate) on the asbestos mesh and extinguish the alcohol lamp.
5. When the crucible (or glass plate) has cooled, consider the substance that is in the crucible (or on the glass plate).
1) Has the paraffin wax changed?
2) Did you get a new substance when heating paraffin?
3) What is this phenomenon: physical or chemical?
Examples of chemical phenomena.
Experience No. 3. Annealing a copper plate or wire
in the flame of an alcohol lamp.
Equipment and reagents: spirit lamp, matches, crucible tongs or test tube holder, asbestos mesh, copper wire or plate.
Instructions for performing the experiment.
1. Take the copper plate (or copper wire) with crucible tongs.
2. Place a copper plate on top of the spirit lamp flame and heat it up.
3. After 1-2 minutes, remove the plate from the flame and peel off from it with a knife or a splinter the formed black plaque on a blank sheet of paper.
4. Repeat heating and clean off the resulting plaque again.
5. Compare the resulting black coating with the copper strip.
1) Has the copper plate changed during incandescence?
2) Was a new substance formed when the copper plate was heated?
3) What is this phenomenon: physical or chemical?
Experience No. 4. The action of hydrochloric acid on chalk or marble.
Equipment and reagents: a 50 ml beaker, marble (small pieces or chips), hydrochloric acid solution (1: 3), matches.
Instructions for performing the experiment.
1. Place 2-3 small pea-sized pieces of marble in a beaker. Be careful not to break the bottom of the glass.
2. Pour enough hydrochloric acid into the glass so that the pieces of marble are completely covered with it. What are you watching?
3. Light a match and place it in a glass. What are you watching?
4. Perform a drawing of the experiment, write down your observations.
1) Was a new substance formed when hydrochloric acid was added to the marble? What kind of substance is it?
2) Why did the match go out?
3) What is this phenomenon: physical or chemical?
Types of chemical reactions.
The demonstration experiment and many practical works are based on the use of simple chemical devices. In addition to getting acquainted with the chemical transformations of substances, students should understand the physical essence of what is happening, and be able to explain the essence of what is happening by the drawing of the device: what is going where and what is happening where.
One of the instruments in the chemistry room is a gas meter. In fig. 1 shows a gas meter filled with gas. It can be oxygen, as shown in the figure, carbon dioxide, or just air. Cranes 1 and 2 at this moment are closed. Gas, in accordance with Pascal's law, exerts pressure on the walls of the vessel and on the water. Opening the tap 1 , the column of water from the funnel puts pressure on the gas, pressing it, but since internal gas pressure and water pressure are balanced, nothing happens. Opening the tap 2 , the gas rushes into the outlet (the flow rate is regulated by a careful turning of the valve). The pressure inside the vessel drops - and water from the funnel enters the gasometer. After closing the tap 2 gas extraction stops, the water level is set at a higher mark, because there is a new balance of power. The tap is closed to stop the water pressure. 1 .
The second device, similar to a gas meter, is the Kipp apparatus (Fig. 2). This device can produce hydrogen from zinc and hydrochloric acid (see Fig. 2), hydrogen sulfide from iron sulfide, carbon dioxide from marble. In position a the device is in working order, the tap is open. A strong solution of hydrochloric acid rushes to the bottom of the device, fills it and wets the metallic zinc lying on the copper grid. Zinc dissolves in acid, reacts with it, the resulting hydrogen rushes into the middle sphere of the device, displaces the air, mixing with it. Therefore, the escaping gas must be checked for cleanliness. The distribution of physical forces in the device is shown in Fig. 2 using the arrows.
We close the tap. Hydrogen continues to form, and its amount increases. Since the gas outlet is blocked, pressure increases inside the sphere. It squeezes the acid out of the middle sphere until the acid stops coating the zinc surface. The chemical reaction stops (zinc wetted with acid continues to react with it for some time). The internal pressure in the device, generated by hydrogen, and the pressure created by hydraulic valve, are balanced.
Consider methods for collecting gases. In fig. 3 shows how to collect gas using the air displacement method. If the gas is toxic, this operation is carried out in a fume hood. Gases that are heavier than air - CO 2, O 2, HCl, SO 2, entering a jar or beaker, displace the air.
When studying carbon dioxide: its physical properties and inability to sustain combustion of organic matter - demonstrated entertaining experience extinguishing burning in air paraffin candle(fig. 4). Carbon dioxide, as a heavier gas, goes down under the force of gravity. It fills the container and displaces the air it contains. The candle goes out in an atmosphere of carbon dioxide.
The device shown in Fig. 5, students collect on practical work "Obtaining oxygen and studying its properties." This device illustrates the method of collecting gas by air displacement (the physical basis for relative density).
Another method of collecting gases is associated with the displacement of water from the vessel. In this way, it is possible to collect gases that are slightly soluble in water, in particular nitric oxide (II) (Fig. 6). Reactor gas 1 enters the gas outlet pipe 2 placed under the upside-down cylinder 3 ... Passing through the water column, the gas collects in the area of the cylinder bottom. Under gas pressure, water is pushed out of the cylinder.
If the gas is poorly soluble in water, then this gas can
but saturate the water as shown in fig. 7. In such a device, you can get chlorine (see Fig. 7) or sulfur dioxide by adding concentrated sulfuric acid to sodium sulfite crystals. The gas obtained in the Würz flask enters the gas outlet tube, which is immersed in water at the end. The gas partially dissolves in water, partially fills the space above the water, displacing the air.
If the gas is highly soluble in water, then it cannot be collected by water displacement. In fig. Figures 8 and 9 show how the hydrogen chloride and ammonia are collected by the air displacement method. The same fig. 8 and 9
(see p. 22) shows the dissolution of gases when immersed tubes with HCl and NH 3 hole in water.
If you saturate with hydrogen chloride from a test tube (with reagents) with a gas outlet tube dipped in water (Fig. 10), then the first portions of gas instantly dissolve in water. About 500 liters of hydrogen chloride dissolves in 1 liter of water, therefore, the incoming gas does not create overpressure... In fig. 10 a consistent change in gas pressure is noted p int in a reaction tube with respect to atmospheric pressure p atm. The pressure inside the device becomes less than the external pressure, and water rapidly fills the gas outlet pipe and the device itself. In addition to spoiling the experiment, the test tube may crack.
When studying the chemical properties of metallic sodium (Fig. 11), it is important not only to observe its behavior in reaction with water, but also to explain the observed phenomena. The first observation is that sodium remains on the surface of the water, therefore, its density is less than one (the density of water). The second observation is that sodium "rushes" through the water due to the repulsive effect of the released gas. The third observation is that sodium melts and turns into a ball. Sodium react with water is exothermic. The released heat is enough to melt sodium, therefore, it is a low-melting metal. The fourth observation is that the reaction is accompanied by outbreaks; therefore, the heat of reaction is sufficient both for the spontaneous combustion of sodium and for the microexplosion of hydrogen. If the reaction is carried out in a narrow space (in a test tube), and even with a large piece of sodium, then the explosion of hydrogen cannot be avoided. To avoid an explosion, the reaction is carried out in a crystallizer or in a large-diameter beaker and using a small piece of sodium.
It is necessary to pay great attention to the rule of dissolving concentrated sulfuric acid in water (Fig. 12). The acid, as a heavier liquid, rushes to the bottom of the round-bottomed flask. Everything else is shown in fig. 12.
The formation of physicochemical thinking is facilitated by the study of oxygen (both in the initial course of chemistry and in the course of organic chemistry). We are talking about the use of oxygen and acetylene in welding and autogenous metal cutting (Fig. 13). When welding, a high-temperature flame of acetylene burning in oxygen (up to 2500 ° C) is directed to the metal wire and the place to be welded. The metal melts, you get a seam. In autogenous cutting, the flame melts the metal, and the excess oxygen burns it out.
Not every chemistry classroom contains silicon as a simple substance. Let's check it for electrical conductivity using a simple device: a probe with elastic elongated iron ends, a light bulb (mounted on a stand), and an electric wire with a plug (Fig. 14). The lamp glows, but not brightly - it is clear that silicon conducts an electric current, but provides significant resistance to it.
The chemical element silicon is an analogue of carbon, but the radius of its atoms is greater than the radius of carbon atoms. Silicon, as a simple substance, has the same (as diamond) crystal lattice (atomic) with a tetrahedral orientation of chemical bonds. In a diamond, covalent bonds are strong; it does not conduct an electric current. In silicon, as even a rough experiment shows, some part of the electron pairs is vaporized, which causes some electrical conductivity of the substance. In addition, silicon heats up (some students have the opportunity to verify this), which also indicates the resistance of the substance to electric current.
Students observe with great interest the study of the physical and chemical properties of benzene (Fig. 15). Add a layer of benzene ~ 2 mm thick to a small amount of water (see Fig. 15, a). It can be seen that the two colorless liquids do not mix. Mix this stratified mixture with vigorous shaking, we get a "gray" emulsion. We fix the tube in an upright position. Students observe a gradual separation of benzene and water, and at first the lower level of the content becomes transparent, and after a short time we obtain the initial distribution. Water molecules are lighter than benzene molecules, but their density is somewhat higher. The interaction between non-polar benzene molecules and polar water molecules is insignificant, very weak, so most of the benzene is pushed out to the water surface (see Fig. 15, b).
Now add benzene to a few milliliters of bromine water (low color intensity) (see Fig. 15, b). The fluids are immiscible. Mix vigorously the contents of the test tube and let the system settle. Bromine, previously dissolved in water, is extracted into the benzene layer, which is evident from the color change and an increase in its intensity.
Add a few milliliters of a weak alkali solution to the contents of the test tube.
(see fig. 15, b). Bromine reacts with alkali. The benzene layer is discolored, and the formed inorganic substances and water pass into the lower (water) layer.
In this article, we limited ourselves to examples that illustrate not just the connection between teaching chemistry and physics, but compensate for the lack of textbooks in which the named physical phenomena, as a rule, are not reflected.
PRACTICAL WORK (1 h) 8 CLASS
The work is carried out by students independently under the supervision of a teacher.
I offer the result of my many years of work on the preparation and implementation of practical work in comprehensive school in chemistry lessons in grades 8-9:
All of them have been tested by me in the classroom. They can be used when studying a school chemistry course as new program O.S. Gabrielyan, and according to the program of G.E. Rudzitis, F.G. Feldman.
Student experiment is a kind independent work... The experiment not only enriches students with new concepts, abilities, skills, but is also a way to test the truth of the knowledge they have acquired, contributes to a deeper understanding of the material, the assimilation of knowledge. It allows you to more fully implement the principle of variability of perception of the surrounding world, since the main essence of this principle is the connection with life, with the future practical activities of students.
Goals... To be able to obtain oxygen in the laboratory and collect it by two methods: displacement of air and displacement of water; to confirm empirically the properties of oxygen; know the safety rules.
Equipment... A metal stand with a foot, an alcohol lamp, matches, a test tube with a gas outlet tube, a test tube, a cotton ball, a pipette, a beaker, a splinter, a dissecting needle (or wire), a crystallizer with water, two conical flasks with stoppers.
Reagents... KMnO 4 crystalline (5-6 g), lime water Ca (OH) 2, charcoal,
Fe (steel wire or paper clip).
Safety rules.
Handle chemical equipment with care!
Remember! The test tube is warmed up, holding it in an inclined position, along its entire length, with two or three movements in the flame of an alcohol lamp. When heating, direct the opening of the tube away from yourself and your neighbors.
Pre-learners receive homework, connected with the study of the content of the forthcoming work according to the instructions, at the same time using the materials of the 8th grade textbooks by the authors O.S. Gabrielyan (§ 14, 40) or G.E. Rudzitis, F.G. Feldman (§ 19, 20). In notebooks for practical work, they write down the name of the topic, the purpose, list the equipment and reagents, draw up a table for the report.
DURING THE CLASSES
I put one experience higher
than a thousand opinions
born only
imagination.
M.V. Lomonosov
1. Place potassium permanganate (KMnO 4) into a dry test tube. Place a loose cotton ball at the opening of the test tube.
2. Close the test tube with a stopper with a gas outlet tube, check for leaks (Fig. 1).
|
Rice. 1.
|
(Explanations of the teacher on how to test the device for leaks.) Mount the device in the tripod leg.
3. Lower the gas outlet tube into the glass, without touching the bottom, at a distance of 2-3 mm (Fig. 2).
4. Heat the substance in the test tube. (Remember the safety rules.)
5. Check for gas with a smoldering speck (coal). What are you watching? Why can oxygen be collected by air displacement?
6. Collect the resulting oxygen in two flasks for the following experiments. Cap the flasks.
7. Prepare the report using the table. 1, which you place on the spread of your notebook.
1. Fill the tube with water. Close the tube with your thumb and turn it upside down. In this position, lower your hand with the test tube into the crystallizer with water. Bring the test tube to the end of the gas outlet tube without removing it from the water (Fig. 3).
2. When oxygen has displaced water from the tube, close it with your thumb and remove it from the water. Why can oxygen be collected by displacing water?
Attention! Remove the gas outlet tube from the crystallizer, without stopping heating the tube with KMnO 4. If this is not done, then the water will be transferred to a hot test tube. Why?
1. Attach the ember to a metal wire (dissecting needle) and bring it into the flame of an alcohol lamp.
2. Dip a red-hot coal into a flask with oxygen. What are you watching? Give an explanation (fig. 4).
3. After removing unburned coal from the flask, pour 5-6 drops of lime water into it
Ca (OH) 2. What are you watching? Give an explanation.
4. Fill out a report on the work in table. 1.
1. Attach a piece of a match to one end of the steel wire. Light a match. Dip the wire with a burning match into a flask with oxygen. What are you watching? Give an explanation (fig. 5).
2. Fill out a report on the work in table. 1.
Table 1
| Operations performed (what they were doing) |
Figures with the designation of the starting and obtained substances | Observations. Conditions carrying out reactions. Reaction equations |
Explanations of observations. conclusions |
|---|---|---|---|
| Assembling the device for obtaining oxygen. Checking the device for leaks | |||
| Oxygen production from KMnO 4 when heated |
|||
| Proof of oxygen production with smoldering splinter |
|||
| Characteristics of the physical properties of O 2. Collection of O 2 by two methods: air displacement, water displacement |
|||
| Characteristic chemical properties of O 2. Interaction with simple substances: burning coal, burning iron (steel wire, paper clip) |
Make a written summary of the work done (5 min).
OUTPUT... One of the ways to obtain oxygen in the laboratory is to decompose KMnO 4. Oxygen is a colorless and odorless gas, 1.103 times heavier than air ( M r(O 2) = 32, M r(air) = 29, from which it follows 32/29 1.103), slightly soluble in water. Reacts with simple substances to form oxides.
Bring workplace in order (3 minutes): disassemble the appliance, arrange the dishes and accessories in their places.
Submit your notebooks for review.
Homework.
Task... Determine which of the iron compounds - Fe 2 O 3 or Fe 3 O 4 - is richer in iron?
| Given: | Find: |
| Fe 2 O 3, Fe 3 O 4. |
(Fe) in Fe 2 O 3, "(Fe) in Fe 3 O 4 |
Solution
(X) = n A r(X) / M r, where n- the number of atoms of element X in the formula of a substance.
M r(Fe 2 O 3) = 56 2 + 16 3 = 160,
(Fe) = 56 2/160 = 0.7,
(Fe) = 70%,
M r(Fe 3 O 4) = 56 3 + 16 4 = 232,
"(Fe) = 56 3/232 = 0.724,
"(Fe) = 72.4%.
Answer... Fe 3 O 4 is richer in iron than Fe 2 O 3.
The teacher, during practical work, observes the correctness of the implementation of techniques and operations by students and notes in the card of the account of skills (Table 2).
table 2
| Practical work operations | Surnames of students | |||||
|---|---|---|---|---|---|---|
| A | B | V | G | D | E | |
| Oxygen production device assembly | ||||||
| Checking the device for leaks | ||||||
| Strengthening the tube in the tripod leg | ||||||
| Handling an alcohol lamp | ||||||
| Heating a test tube with KMnO 4 | ||||||
| O 2 emission check | ||||||
| Collecting O 2 into a vessel by two methods: air displacement, water displacement |
||||||
| Burning coal | ||||||
| Combustion Fe (steel wire) | ||||||
| Experiment culture | ||||||
| Registration of work in a notebook | ||||||
Lime water becomes cloudy, because a water-insoluble precipitate CaCO 3 is formed:
CO 2 + Ca (OH) 2 CaCO 3 + H 2 O. Iron burns with a bright flame in oxygen:
Test "Nitrogen and its compounds"
Option 1 1. Strongest Molecule: a) H 2; b) F 2; c) O 2; d) N 2. 2. Coloring of phenolphthalein in ammonia solution: a) crimson; b) green; c) yellow; d) blue. 3. The oxidation state is +3 at the nitrogen atom in the compound: a) NH 4 NO 3; b) NaNO 3; c) NO 2; d) KNO 2. 4. Thermal decomposition of copper (II) nitrate produces:a) copper (II) nitrite and O 2 ; b) nitric oxide (IV) and О 2 ; c) copper (II) oxide, brown gas NO 2 and O 2; d) copper (II) hydroxide, N 2 and O 2. 5. What ion is formed by the donor-acceptor mechanism? a) NH 4 +; b) NO 3 -; c) Cl -; d) SO 4 2–. 6. Indicate strong electrolytes: a) nitric acid; b) nitrous acid; v) water solution ammonia; d) ammonium nitrate. 7. Hydrogen is released during the interaction: a) Zn + HNO 3 (dil.); b) Cu + HCl (solution); c) Al + NaOH + H 2 O; d) Zn + H 2 SO 4 (dil.); e) Fe + HNO 3 (conc.). 8. Write the equation for the reaction of zinc with very dilute nitric acid if one of the reaction products is ammonium nitrate. Indicate the coefficient in front of the oxidizing agent. 9.Give names to substances A, B, C. Option 2 1. By displacing water it is impossible to collect: a) nitrogen; b) hydrogen; c) oxygen; d) ammonia. 2. The reagent for the ammonium ion is a solution of: a) potassium sulfate; b) silver nitrate; c) sodium hydroxide; d) barium chloride. 3. With the interaction of НNО 3 (conc.) gas is formed with copper shavings: a) N 2 O; b) NH 3; c) NO 2; d) H 2. 4. Thermal decomposition of sodium nitrate forms: a) sodium oxide, brown gas NO 2, O 2; b) sodium nitrite and O 2; c) sodium, brown gas NO 2, O 2; d) sodium hydroxide, N 2, O 2. 5. Oxidation degree of nitrogen in ammonium sulfate: a) –3; b) –1; c) +1; d) +3. 6. Which of these substances does concentrated HNO react with? 3 under normal conditions? a) NaOH; b) AgCl; c) Al; d) Fe; e) Cu. 7. Specify the number of ions in the abbreviated ionic equation for the interaction of sodium sulfate and silver nitrate: a) 1; b) 2; at 3; d) 4. 8. Write the equation for the interaction of magnesium with dilute nitric acid if one of the reaction products is a simple substance. Indicate the coefficient in front of the oxidizer in the equation. 9. Write the reaction equations for the following transformations:
Give names to substances A, B, C, D.
Answers
Option 1 1 - G; 2 - a; 3 - G; 4 - v; 5 - a; 6 - a, d; 7 - c, d; 8 – 10,
2Ag + + SO 4 2– = Ag 2 SO 4;
8 – 12, 9.A - NO, B - NO 2, C - HNO 3, D - NH 4 NO 3,
