What is Sulfa

Preparing for the exam in chemistry and olympiads

Task 32 on the Unified State Exam in Chemistry 2018 (the former task C2 of a “new type”) contains a description of an experiment consisting of successively conducted chemical reactions and laboratory methods of separating reaction products (a mental experiment).

According to my observations, for many students this task causes difficulties. To a large extent, this is due to the increasingly academic nature of chemistry teaching in schools and courses, when insufficient attention is given to studying the characteristics of working in the laboratory and actually conducting laboratory experiments.

Therefore, I decided to systematize and summarize the material on

To perform this task, you need a good understanding of some topics of general chemistry and chemistry of elements, namely: the main classes of inorganic substances , chemical properties and oxide production , acids, bases and salts, and the relationship between different classes of inorganic substances; properties of simple substances – metals and non-metals; hydrolysis ; electrolysis; oxidation-reduction reactions (OVR), main oxidizers and reducing agents, and their transformations under different conditions, the main types of IAD, chemistry of alkali metals and their compounds, alkaline earth metals and compounds, carbon, silicon, nitrogen, phosphorus, sulfur, halogens.

  1. The solution obtained by reacting copper with concentrated nitric acid was evaporated and the precipitate was calcined. The gaseous decomposition reaction products are completely absorbed by water, and hydrogen is passed over the solid residue. Write the equations of the reactions described.

Analysis and solution.

“Keywords” – concentrated nitric acid and copper.

Copper is a low-active metal, exhibits the properties of a reducing agent.

The oxidizing properties of nitric acid determine nitrogen in the oxidation state +5, therefore, when interacting with metals and with other reducing agents, it is not hydrogen that is released, but a substance containing nitrogen in lower oxidation states; concentrated nitric acid dissolves low-active metals and is reduced to NO2 (equation 1).

“Keywords” – … the precipitate was calcined. The nitrates of metals in the range of activity from magnesium to copper, decompose when heated to metal oxide, brown gas and oxygen (equation 2).

“Keywords” – … missed the hydrogen. Reduction of metal oxides with hydrogen is one of the methods for producing metals (equation 3).

“Keywords” – Gaseous products … absorbed by water …. The decomposition of copper nitrate produces NO2 and O2. Nitrogen and nitric acids correspond to nitric oxide (IV), but in the presence of an oxidizing agent — molecular oxygen, only nitric acid is formed in the solution (Eq. 4).

3) CuO + H2 = Cu + H2O

  1. A simple substance, obtained by heating calcium phosphate with coke and silica, was fused with metallic calcium. The reaction product was treated with water, and the evolved gas was collected and passed through a solution of hydrochloric acid. Write the equations of the reactions described.

Analysis and Solution

“Keywords” – … heating calcium phosphate with coke and silica … . The first of the described transformations is an industrial method for the production of phosphorus (equation 1).

“Keywords” – A simple substance … fused with calcium.

The simple substance formed in the first transformation is phosphorus. Metals (reducing agents) interact with non-metals (oxidizing agents) to form binary compounds (salts or oxides) (equation 2).

“Keywords” – The product … was treated with water … When Ca3P2 phosphide interacts with water, hydrolysis occurs (Eq. 3) and calcium hydroxide Ca (OH) 2 and phosphine PH3, gas with garlic odor are formed.

“Keywords” – … gas … hydrochloric acid solution. Phosphine, being an analogue of ammonia, exhibits basic properties and reacts with an acid to form the phosphonium salt PH4Cl (equation 4).

one) Ca3 (P +5 O4) 2 + 5 C 0 + 3SiO2 = 3CaSiO3 + 2 P 0 + 5 C +2 O

2) 2P + ZSa = Ca3P2

4) PH3 + HCl = PH4Cl

  1. The precipitate obtained by the interaction of solutions of iron (III) chloride and silver nitrate was filtered. The filtrate was treated with potassium hydroxide solution. The brown precipitate was separated and calcined. The resulting substance reacts with aluminum with heat with the release of heat and light. Write the equations of the reactions described.

Analysis and solution.

Keywords: “… interaction of solutions of iron (III) chloride and silver nitrate… ” When two soluble salts interact, an ion exchange reaction takes place if there is a low dissociating substance in the reaction products (gas, precipitate, water, etc.). The interaction of silver nitrate and iron (III) chloride gives a white, cheesy precipitate of silver chloride (equation 1).

Next, the precipitate was filtered. Filtration – a method of separation of mixtures in which water-insoluble substances do not pass through a thin porous partition ( filter ), and water-soluble substances with a solvent ( filtrate ) go into a separate container.

When this solution is filtered in the solution, silver-insoluble silver chloride remains in the sediment, and the water-soluble salt, iron (III) nitrate, goes to the filtrate.

Next, the keywords: “… the filtrate was treated with potassium hydroxide solution. “. In the interaction of iron (III) nitrate with potassium hydroxide KOH, an exchange reaction takes place, with the formation of a water-insoluble precipitate — iron (III) hydroxide (reaction 2).

Next, the keywords: ” The brown precipitate was separated and calcined. “. Iron (III) hydroxide is a water-insoluble base. As a rule, insoluble bases decompose upon calcination into metal oxide and water (reaction 3).

Further ” When heated, the substance obtained reacts with aluminum with the release of heat and light. “. This description corresponds to the redox reaction between iron (III) oxide and aluminum. When the mixture of these compounds is heated, the exothermic reaction of the reduction of iron to a simple metal substance occurs, and heat is also released in the form of light. The reduction of metals from oxides using aluminum is called aluminothermia .

one) FeCl3 + 3AgNO3 = 3AgCl + Fe (NO3) 3

4. A substance obtained at the cathode during the electrolysis of molten sodium chloride was burned in oxygen. The resulting product was sequentially treated with sulfur dioxide and barium hydroxide solution. Write the equations of the reactions described.

Analysis and solution.

First part: “… during the electrolysis of molten sodium chloride“. Electrolysis – This is a chemical reaction occurring under the action of current. During the electrolysis of molten salts at the cathode, the reduction of metals to simple substances occurs, at the anode – the oxidation of non-metals to simple substances (equation 1).

Next, the keywords: “The substance obtained at the cathode … burned in oxygen“. During the electrolysis of molten sodium chloride, metallic sodium is released at the cathode. When burned, the simple substance sodium forms predominantly peroxide (equation 2).

Keywords: “The resulting product … treated with sulfur dioxide“. Sodium peroxide, like hydrogen peroxide, exhibits dual properties, and can act as both an oxidizing agent and a reducing agent. Sulfur dioxide SO2 is a typical reducing agent. When interacting with sulfur dioxide, sodium peroxide oxygen acts as an oxidizing agent and is reduced to oxidation state -2 (equation 3). Read more about OVR – in the article “Redox Reactions”.

Keywords: ” … The resulting product was sequentially treated with sulfur dioxide and a solution of barium hydroxide“. Sodium sulfate, obtained in the previous stage, enters into ion exchange reaction with barium hydroxide with precipitation of barium sulfate (equation 4).

one) 2NaCl = 2Na + Cl2

5. The decomposition products of ammonium chloride are successively passed through a heated tube containing copper (II) oxide, and then through a flask with phosphorus oxide (V). Write the equations of the reactions described.

Analysis and solution.

Keywords: “Ammonium chloride decomposition products… ” Ammonium chloride – a salt that decomposes when a solid salt is heated to gaseous ammonia and hydrogen chloride gas (equation 1)

Next, the decomposition products are successively passed through a heated tube containing copper (II) oxide. Sequentially, it means they react in turn. Copper (II) oxide is basic, when interacting with acid HCl forms salt and water (equation 2). Copper (II) oxide also exhibits oxidative properties, when interacting with ammonia, it is reduced to a simple substance, copper, and ammonia is also oxidized to a simple substance (equation 3). Read more about OVR – in the article “Redox Reactions”.

Next, the products of reactions 2 and 3 are passed through a tank with phosphorus oxide (V). We analyze the possibility of a chemical reaction between substances. Simple matter copper is chemically inactive and does not react with acidic phosphorus oxide. Simple substance nitrogen is also chemically inactive, it does not react with phosphorus oxide (V). On the other hand, water vapor reacts well with acidic phosphorus (V) oxide to form ortho-phosphoric acid (equation 4).

1) NH4Cl = NH3 + HCl

2) CuO + 2HCl = CuCl2 + H2O

3) 3CuO + 2NH3 = 3Cu + N2 + 3H2O

6 A white salt insoluble in water, which is found in nature as a mineral widely used in construction and architecture, was added with a solution of hydrochloric acid, as a result of which the salt dissolved and a gas evolved, which passed a white precipitate through lime water; the precipitate dissolved with further gas transmission. When boiling the resulting solution precipitates. Write the equations of the reactions described.

Analysis and solution.

It is well known from the school chemistry course that white water insoluble salt, which is found in nature as a mineral widely used in construction and architecture is calcium carbonate CaCO3. Insoluble salts dissolve under the action of stronger acids, in this case, hydrochloric acid (equation 1).

Gas generated passed through lime water Ca (OH) 2. Carbon dioxide is a typical acidic oxide, which, in contact with alkali, forms a salt — calcium carbonate (equation 2). Further the precipitate dissolved with further gas transmission. Here is considered a very important property: medium salts of polybasic acids form more acidic salts by the action of excess acid . Calcium carbonate in an excess of carbon dioxide gas forms a more acidic salt — calcium bicarbonate Ca (HCO3) 2, which is highly soluble in water (equation 3).

The properties of acid salts largely consist of the properties of the compounds forming acid salts. The properties of calcium bicarbonate are determined by the properties of the compounds forming it — carbonic acid H2CO3 and calcium carbonate. It is easy to deduce that, when boiling, the bicarbonate will decompose to calcium carbonate (decomposed at higher temperatures, on the order of 1200 degrees Celsius), carbon dioxide and water (equation 4).

7. Substance received on the anode during the electrolysis of a solution of sodium iodide with inert electrodes, reacted with hydrogen sulfide. The solid formed is alloyed with aluminum and the product is dissolved in water. Write the equations of the reactions described.

Analysis and solution.

Electrolysis of sodium iodide solution with inert electrodes is described by the equation:

1. 2NaI + 2H2O = 2NaOH + H2 + I2

More information about electrolysis can be found in the relevant article. In this case, iodine is released on the anode. Iodine reacts with hydrogen sulfide. In this case, iodine is an oxidizing agent, and sulfur is a reducing agent:

2. I2 0 + H2 S -2 = 2H I – + S 0

At the same time solid sulfur was formed. Sulfur reacts with aluminum during fusion to form aluminum sulphide. Most nonmetals react with metals to form binary compounds:

3. 3 S 0 + 2 Al 0 = Al2 +3 S3 -2

The product of the reaction of aluminum with sulfur, aluminum sulfide, when dissolved in water, is irreversibly decomposed into aluminum hydroxide and hydrogen sulfide:

Such reactions are also called reactions. irreversible hydrolysis . Details of cases of irreversible hydrolysis are discussed in the article.

8. The gas released by the interaction of hydrogen chloride with potassium permanganate reacts with iron. The reaction product was dissolved in water and sodium sulfide was added to it. The lighter of the formed insoluble materials was separated and reacted with hot concentrated nitric acid. Write the equations of the reactions described.

9. Chromium (III) sulfide was treated with water, while gas evolved and an insoluble substance remained. A solution of caustic soda was added to this substance and chlorine gas was missed, while the solution acquired a yellow color. The solution was acidified with sulfuric acid, as a result, the color changed to orange; the gas emitted during the treatment of the sulfide with water was passed through the resulting solution, and the color of the solution changed to green. Write the equations of the reactions described.

Analysis and solution.

Keywords: “Chromium (III) sulfide was treated with water, while gas evolved and an insoluble substance remained“. Chromium (III) sulfide under the action of water decomposes into hydroxide and hydrogen sulfide . Details of the hydrolysis reaction of such compounds are discussed in the article “Hydrolysis”. (reaction 1)

Keywords: “… added a solution of caustic soda and missed gaseous chlorine, while the solution acquired a yellow color“. Under the action of chlorine in an alkaline environment, chromium +3 is oxidized to chromium +6 . Chromium +6 forms an acid oxide and hydroxide, in a solution of caustic sodium forms a stable yellow salt — sodium chromate (reaction 2).

2) 2 Cr +3 (OH) 3 + 3 Cl 0 2 + 10NaOH = 2Na2 Cr + 6 O4 + 6Na Cl – + 8H2O

Next, the keywords: “The solution was acidified with sulfuric acid, as a result, the color changed to orange“. The acid chromate salts are converted to dichromates. Yellow sodium chromate in an acidic medium turns into orange sodium dichromate (reaction 3). This is not iad!

Further: “… the gas emitted during the treatment of the sulfide with water was passed through the solution obtained, and the solution color changed to green“. Sodium dichromate is a strong oxidizing agent; when interacting with hydrogen sulfide, it is reduced to the trivalent chromium salt. Chromium (III) compounds are amphoteric, form salts in an acidic medium. Chromium (III) salts stain the solution green (reaction 4).

10. Getting a black and white image when photographing is based on the decomposition of salt of an unknown metal under the action of light. When this metal is dissolved in dilute nitric acid, a colorless gas is released, which rapidly changes its color to brown in air, and salt is formed, which interacts with sodium bromide to form a yellowish cheesy precipitate. The anion in the salt used in photography is the acid anion, which is formed simultaneously with sulfuric acid, in the interaction of bromine water and sulfur dioxide. Write the equations of the reactions described.

11. Sodium hydroxide solution was added dropwise to the solution obtained by reacting aluminum with dilute sulfuric acid. The precipitated white precipitate was filtered and calcined. The resulting substance is fused with sodium carbonate. Write the equations of the reactions described.

Analysis and solution.

Diluted sulfuric acid behaves as an ordinary mineral acid when interacting with metals. Metals that are in the series of electrochemical activity to the left of hydrogen, when interacting with mineral acids, displace hydrogen :

Further, aluminum sulfate interacts with sodium hydroxide. The condition indicated that sodium hydroxide was added dropwise. This means that sodium hydroxide was deficient, and aluminum sulfate, in significant excess. Under these conditions, a precipitate of aluminum hydroxide forms:

The white precipitate is aluminum hydroxide, insoluble in water. When calcining, insoluble hydroxides decompose into water and the corresponding oxide. :

The resulting substance, alumina, was fused with sodium carbonate. In the melt, less volatile oxides displace more volatile of the salts. Carbonate is the salt to which the volatile oxide, carbon dioxide, corresponds. Accordingly, when alloying carbonates of alkali metals with solid oxides (acidic and amphoteric), a salt is formed, corresponding to this oxide, and carbon dioxide:

12. A constant electric current was passed through a solution of copper (II) chloride using graphite electrodes. The electrolysis product released at the cathode was dissolved in concentrated nitric acid. The resulting gas was collected and passed through a solution of sodium hydroxide. The gaseous electrolysis product released at the anode was passed through a hot sodium hydroxide solution. Write the equations of the reactions described.

13. A simple substance obtained by heating a mixture of calcium phosphate with coke and silica is dissolved in a solution of caustic potash. The gaseous substance released was burned, the combustion products were collected and cooled, and silver nitrate was added to the resulting solution. Write the equations of the reactions described.

14. The fetid liquid formed by the interaction of hydrogen bromide with potassium permanganate was separated and heated with iron chips. The reaction product was dissolved in water and a solution of cesium hydroxide was added to it. The resulting precipitate was filtered and calcined. Write the equations of the reactions described.

What is Sulfa

15. Above the surface of the caustic soda solution, electric discharges were allowed in, while the air was colored brown, and the color disappeared after a while. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. Keeping the mixture of salts in air leads to the formation of one substance. Write the equations of the reactions described.

Calcium is dissolved in water. By passing a sulfurous gas through the resulting solution, a white precipitate is formed, which dissolves when an excess of gas is passed. Adding to the resulting solution of alkali leads to the formation of a white precipitate. Write the equations of the reactions described.

When a simple yellow substance is burned in air, a gas with a strong odor is formed. This gas is also released during the burning of some mineral containing iron in air. When diluted sulfuric acid acts on a substance consisting of the same elements as the mineral, but in a different ratio, gas with a characteristic smell of rotten eggs is released. In the interaction of the evolved gases with each other, the original simple substance is formed. Write the equations of the reactions described.

The gaseous product of the interaction of dry sodium chloride with concentrated sulfuric acid was reacted with potassium permanganate solution. The released gas was passed through a solution of sodium sulfide. The yellow precipitate formed is dissolved in a concentrated sodium hydroxide solution. Write the equations of the reactions described.

The gas formed by passing hydrogen chloride through a hot solution of potassium chromate, interacts with iron. The reaction product was dissolved in water and sodium sulfide was added to it. The lighter of the formed insoluble materials was separated and reacted with concentrated sulfuric acid by heating. Write the equations of the reactions described.

Two salts contain the same cation. The thermal decomposition of the first of them resembles a volcanic eruption, while a low-active colorless gas is released, which is part of the atmosphere. When a second salt interacts with a solution of silver nitrate, a white, cheesy precipitate forms, and when heated with an alkali solution, a colorless poisonous gas with a strong odor is released; this gas can also be obtained by reacting magnesium nitride with water. Write the equations of the reactions described.

An excess of sodium hydroxide solution was added to the aluminum sulfate solution. Hydrochloric acid was added to the resulting solution in small portions, and the formation of a white solid precipitate was observed, which dissolved with further acid addition. Sodium carbonate solution was added to the resulting solution. Write the equations of the reactions described.

Above the surface of the caustic soda solution poured into the flask, electric discharges were passed, while the air in the flask was colored a brown color, which disappeared after a while. The resulting solution was carefully evaporated and the solid residue was found to be a mixture of two salts. When this mixture is heated, gas is released and only a single substance remains. Write the equations of the reactions described.

Zinc oxide was dissolved in hydrochloric acid solution and the solution was neutralized by adding caustic soda. The white gelatinous substance that separated was separated and treated with an excess of alkali solution, and the precipitate completely dissolved. Neutralization of the resulting solution with an acid, for example, nitric acid, leads to the re-formation of a gelatinous precipitate. Write the equations of the reactions described.

The substance obtained at the cathode during the electrolysis of the copper (II) chloride melt reacts with sulfur. The resulting product was treated with concentrated nitric acid and the evolved gas was passed through a barium hydroxide solution. Write the equations of the reactions described.

A mixture of calcium orthophosphate, coke and sand was heated in an electric furnace. One of the products of this reaction may spontaneously ignite in air. The solid product of combustion of this substance, when heated, was dissolved in water and ammonia gas was passed through the resulting solution. Write the equations of the reactions described.

The substance obtained at the cathode by electrolysis of a solution of iron (II) chloride, was fused with sulfur and the product of this reaction was subjected to roasting. The resulting gas was passed through a solution of barium hydroxide. Write the equations of the reactions described.

A copper wire was introduced into the heated concentrated sulfuric acid and the gas released was passed through an excess of caustic soda solution. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. Unreacted sulfur was separated by filtration and sulfuric acid was added to the solution, and precipitation and gas with a strong odor were observed. Write the equations of the reactions described.

After short-term heating of an unknown powdery orange substance, a spontaneous reaction begins, which is accompanied by a change of color to green, release of gas and sparks. The solid residue was mixed with caustic potash and heated, the resulting substance was added to a dilute hydrochloric acid solution, and a green precipitate formed, which dissolved in an excess of acid. Write the equations of the reactions described.

Two salts paint the flame purple. One of them is colorless, and when it is lightly heated with concentrated sulfuric acid, a liquid is distilled in which copper is dissolved; the last transformation is accompanied by the release of brown gas. When a solution of a sulfuric acid solution is added to the solution, the yellow color of the solution changes to orange, and when the resulting solution is neutralized with alkali, the original color is restored. Write the equations of the reactions described.

Iron (III) chloride solution was electrolyzed with graphite electrodes. The brown precipitate formed as a by-product of electrolysis was filtered and calcined. The substance formed on the cathode was dissolved in concentrated nitric acid when heated. The product released at the anode was passed through a cold solution of potassium hydroxide. Write the equations of the reactions described.

The gas released during the interaction of hydrogen chloride with bertolet salt, introduced into the reaction with aluminum. The reaction product was dissolved in water and sodium hydroxide was added until precipitation stopped, which was separated and calcined. Write the equations of the reactions described.

The unknown salt is colorless and colors the flame yellow. When this salt with concentrated sulfuric acid is lightly heated, a liquid is distilled in which copper is dissolved; The latter transformation is accompanied by the release of brown gas and the formation of a copper salt. In the thermal decomposition of both salts, oxygen is one of the decomposition products. Write the equations of the reactions described.

The substance obtained at the anode during the electrolysis of a melt of sodium iodide with inert electrodes was isolated and brought into contact with hydrogen sulfide. The gaseous product of the last reaction was dissolved in water and ferric chloride was added to the resulting solution. The resulting precipitate was filtered and treated with hot sodium hydroxide solution. Write the equations of the reactions described.

Gases that are released when coal is heated in concentrated nitric and sulfuric acids are mixed together. The reaction products passed through the milk of lime. Write the equations of the reactions described.

A mixture of iron powder and solid product obtained by the interaction of sulfur dioxide and hydrogen sulfide, was heated without air access. The resulting product was calcined in air. The resulting solid reacts with aluminum to produce a large amount of heat. Write the equations of the reactions described.

The black substance was obtained by calcining a precipitate, which is formed by the interaction of solutions of sodium hydroxide and copper (II) sulfate. When this substance is heated with charcoal, a red-colored metal is obtained, which dissolves in concentrated sulfuric acid. Write the equations of the reactions described.

A simple substance, a mixture of which with bertolet salt is used in matches and ignites during friction, burned in an excess of oxygen. A white solid, formed as a result of combustion, was dissolved in an excess of sodium hydroxide solution. The resulting salt with a solution of silver nitrate forms a bright yellow precipitate. Write the equations of the reactions described.

Zinc was dissolved in a very dilute nitric acid and an excess of alkali was added to the resulting solution, resulting in a clear solution. Write the equations of the reactions described.

The solution obtained by passing sulfur dioxide through bromine water was neutralized with barium hydroxide. The precipitate was separated, mixed with coke and calcined. When processing the product of calcination with hydrochloric acid, gas with a smell of rotten eggs is released. Write the equations of the reactions described.

The substance formed by adding zinc powder to the ferric chloride solution was separated by filtration and dissolved in hot dilute nitric acid. The solution was evaporated, the solid residue was calcined, and the evolved gases were passed through a sodium hydroxide solution. Write the equations of the reactions described.

The gas released when the solution of hydrogen chloride with manganese oxide (IV) was heated was reacted with aluminum. The reaction product was dissolved in water and an excess of sodium hydroxide solution was added first, followed by hydrochloric acid (excess). Write the equations of the reactions described.

A mixture of two colorless, colorless and odorless gases, A and B, was passed by heating over an iron-containing catalyst, and the hydrobromic acid solution was neutralized by the gas B produced. The solution was evaporated and the residue was heated with caustic potash; as a result, colorless gas B with a strong odor was released. When gas B is burned in air, water and gas A are generated. Write the equations of the reactions described.

Sulfur dioxide was passed through hydrogen peroxide solution. Water was evaporated from the resulting solution and magnesium chips were added to the residue. The evolved gas was passed through a solution of copper sulphate. The black precipitate was separated and calcined. Write the equations of the reactions described.

A white salt insoluble in water, which is found in nature as a mineral widely used in construction and architecture, was added with a solution of hydrochloric acid. As a result, the salt dissolved and gas evolved, while passing it through lime water, a white precipitate fell out, which dissolved further gas transmission. Adding to the resulting solution, an excess of lime water precipitates. Write the equations of the reactions described.

When some mineral A, consisting of two elements, is burned, a gas is formed that has a characteristic strong odor and bleaches bromine water to form two strong acids in solution. The interaction of substance B, consisting of the same elements as mineral A, but in a different ratio, with concentrated hydrochloric acid produces a poisonous gas with the smell of rotten eggs. The interaction of the gases emitted with each other produces a simple yellow substance and water. Write the equations of the reactions described.

The substance released at the cathode during the electrolysis of the molten sodium chloride was burned in oxygen. The resulting product was placed in a gas meter filled with carbon dioxide. The resulting substance was added to the ammonium chloride solution and the solution was heated. Write the equations of the reactions described.

The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was introduced into a solution of potassium permanganate acidified with sulfuric acid, and the solution became discolored. The nitrogen-containing reaction product was placed in a solution of caustic soda and zinc dust was added, and a gas with a strong characteristic odor was released. Write the equations of the reactions described.

When a salt solution A interacts with an alkali, a gelatinous, water-insoluble blue substance was obtained, which was dissolved in colorless liquid B to form a blue solution. The solid product remaining after careful evaporation of the solution was calcined; at the same time, two gases evolved, one of which is brown in color, and the second is part of atmospheric air, and a black solid substance remains that dissolves in liquid B to form substance A. Write the equations for the reactions described.

White phosphorus is dissolved in a solution of caustic potash with the release of gas with garlic odor, which self-ignites in air. The solid product of the combustion reaction reacted with caustic soda in such a ratio that the resulting white substance contains one hydrogen atom; upon calcination of the last substance, sodium pyrophosphate is formed. Write the equations of the reactions described.

The solution of ferric chloride was acted upon with sodium hydroxide solution, the precipitated precipitate was separated and heated. The solid reaction product was mixed with soda ash and calcined. Both nitrate and sodium hydroxide were added to the remaining substance and heated for a long time at high temperature. Write the equations of the reactions described.

The gas released during the interaction of hydrogen chloride with potassium permanganate, was passed through a solution of sodium tetrahydroxoaluminate. The precipitate formed was filtered, calcined and the solid residue was treated with hydrochloric acid. Write the equations of the reactions described.

The nitric mixture was heated to a temperature of 500 ° C and under a high pressure, it was passed over an iron catalyst. The reaction products were passed through a solution of nitric acid until it was neutralized. The resulting solution was carefully evaporated, the solid residue was calcined and the gas evolved during this was passed over copper when heated, resulting in a black solid substance. Write the equations of the reactions described.

Trivalent chromium hydroxide was treated with hydrochloric acid. Potash was added to the resulting solution, the precipitated precipitate was separated and introduced into a concentrated solution of potassium hydroxide, as a result the precipitate dissolved. After adding an excess of hydrochloric acid, a green solution was obtained. Write the equations of the reactions described.

The substance obtained on the anode by electrolysis of a solution of sodium iodide with inert electrodes, was introduced into the reaction with potassium. The reaction product was heated with concentrated sulfuric acid and the evolved gas was passed through a hot solution of potassium chromate. Write the equations of the reactions described.

Ferrous oxide was heated with dilute nitric acid. The solution was carefully evaporated, the solid residue was dissolved in water, iron powder was added to the resulting solution and filtered after some time. A solution of potassium hydroxide was added to the filtrate, the precipitated precipitate was separated and left in air, while the color of the substance changed. Write the equations of the reactions described.

One of the substances formed by the fusion of silicon oxide with magnesium dissolves in alkali. The released gas was reacted with sulfur, and the product of their interaction was treated with chlorine. Write the equations of the reactions described.

The solid substance formed by the interaction of sulfur dioxide and hydrogen sulfide, when heated, interacts with aluminum. The reaction product was dissolved in dilute sulfuric acid and potash was added to the resulting solution. Write the equations of the reactions described.

Unknown metal burned in oxygen. The reaction product, interacting with carbon dioxide, forms two substances: a solid, which interacts with a solution of hydrochloric acid with the release of carbon dioxide, and a simple gaseous substance that supports combustion. Write the equations of the reactions described.

The product of the interaction of nitrogen and lithium was treated with water. The gas released during the reaction was mixed with an excess of oxygen and, when heated, passed over a platinum catalyst; the resulting gas mixture was brown. Write the equations of the reactions described.

The copper chips were dissolved in dilute nitric acid and the solution was neutralized with caustic potash. The separated blue substance was separated, calcined (the color of the substance changed to black), mixed with coke and re-ignited. Write the equations of the reactions described.

Phosphorus was burned in an excess of chlorine, the resulting solid was mixed with phosphorus and heated. The reaction product was treated with water, while the colorless gas exuded a strong odor. The solution was added to a solution of potassium permanganate acidified with sulfuric acid, which became discolored as a result of the reaction. Write the equations of the reactions described.

Iron chloride was treated by heating with concentrated nitric acid and the solution was carefully evaporated. The solid product was dissolved in water, potash was added to the resulting solution, and the precipitated precipitate was separated and calcined. Hydrogen gas was passed over the obtained substance when heated. Write the equations of the reactions described.

An unknown salt, when interacting with a solution of silver nitrate, forms a white precipitate and colors the flame of the burner in yellow. When a concentrated sulfuric acid interacts with this salt, a poisonous gas is formed that is readily soluble in water. Iron is dissolved in the resulting solution, and a very light, colorless gas is released, which is used to produce metals, for example copper, from their oxides. Write the equations of the reactions described.

The magnesium silicide was treated with a solution of hydrochloric acid and the gas emitted was burned. The solid reaction product was mixed with soda ash, the mixture was heated to melt and held for some time. After cooling, the reaction product (commonly used under the name “liquid glass”) was dissolved in water and treated with a solution of sulfuric acid. Write the equations of the reactions described.

A gas mixture of ammonia and a large excess of air was missed when heated over platinum and the reaction products were absorbed with a solution of caustic soda over time. After evaporation of the solution, a single product was obtained. Write the equations of the reactions described.

Soda ash was added to the ferric chloride solution and the precipitated precipitate was separated and calcined. Above the obtained substance, carbon monoxide was passed by heating, and the solid product of the last reaction was reacted with bromine. Write the equations of the reactions described.

The product of the interaction of sulfur with aluminum (the reaction proceeds with heating) was dissolved in cold dilute sulfuric acid and potassium carbonate was added to the solution. The precipitate was separated, mixed with caustic soda and heated. Write the equations of the reactions described.

Silicon chloride (IV) was heated in a mixture with hydrogen. The reaction product was mixed with magnesium powder, heated and treated with water; one of the substances formed is self-igniting in air. Write the equations of the reactions described.

A brown gas was passed through an excess of caustic potash solution in the presence of a large excess of air. Magnesium chips were added to the resulting solution and heated; evolved gas neutralized nitric acid. The resulting solution was carefully evaporated, the solid reaction product was calcined. Write the equations of the reactions described.

Iron oxide was dissolved in concentrated nitric acid by heating. The solution was carefully evaporated and the reaction product was dissolved in water. Iron powder was added to the resulting solution, after some time the solution was filtered and the filtrate was treated with a solution of potassium hydroxide, as a result a light green precipitate separated which quickly darkened in air. Write the equations of the reactions described.

A solution of aluminum chloride was added to the solution of soda ash, the separated substance was separated and added to caustic soda solution. A solution of hydrochloric acid was added dropwise to the resulting solution until the formation of a precipitate ceased, which was separated and calcined. Write the equations of the reactions described.

Copper chips were added to the mercury (II) nitrate solution. After the reaction, the solution was filtered and the filtrate was added dropwise to the solution containing caustic soda and ammonium hydroxide. At the same time, short-term sediment formation was observed, which dissolved to form a solution of bright blue color. When an excess solution of sulfuric acid was added to the resulting solution, a color change occurred. Write the equations of the reactions described.

The product of the interaction of magnesium phosphide with water burned and the reaction products were absorbed with water. The resulting substance is used in industry to obtain double superphosphate from phosphate. Write the equations of the reactions described.

Salt obtained by the interaction of zinc oxide with sulfuric acid, calcined at 800 ° C. The solid reaction product was treated with a concentrated alkali solution and carbon dioxide was passed through the resulting solution. Write the reactions of the described transformations.

Iron powder was added to the ferric chloride solution and after some time the solution was filtered. Sodium hydroxide was added to the filtrate, the separated precipitate was separated and treated with hydrogen peroxide. An excess solution of potassium hydroxide and bromine was added to the substance obtained; as a result of the reaction, the color of bromine disappeared. Write the equations of the reactions described.

Copper (I) oxide was treated with concentrated nitric acid, the solution was carefully evaporated, and the solid residue was calcined. The gaseous reaction products were passed through a large amount of water and magnesium chips were added to the resulting solution, resulting in a gas used in medicine. Write the equations of the reactions described.

Sulfur dioxide was passed through hydrogen peroxide solution. The solution was evaporated and copper chips were added to the remaining liquid. The released gas was mixed with the gas, which is formed by the interaction of iron (II) sulfide with hydrobromic acid solution. Write the equations of the reactions described.

When yellow salt was added to the solution, which dyed the flame purple, diluted hydrochloric acid, the color changed to orange-red. After neutralizing the solution with concentrated alkali, the color of the solution returned to the original. When barium chloride is added to the resulting solution, a yellow color precipitates. The precipitate was filtered and a solution of silver nitrate was added to the filtrate. Write the equations of the reactions described.

Magnesium silicide was treated with a solution of hydrochloric acid, the reaction product was burned, the resulting solid substance was mixed with soda ash and heated to melt. After cooling the melt, it was treated with water and nitric acid was added to the resulting solution. Write the equations of the reactions described.

The insoluble substance formed by adding sodium hydroxide to the solution of ferric chloride was separated and dissolved in dilute sulfuric acid. Zinc dust was added to the resulting solution, the precipitated precipitate was filtered and dissolved in concentrated hydrochloric acid. Write the equations of the reactions described.

Aluminum nitrate was calcined, the reaction product was mixed with soda ash and heated to melt. The resulting substance was dissolved in nitric acid and the resulting solution was neutralized with an ammonia solution, and a voluminous gelatinous precipitate was observed. Write the equations of the reactions described.

Magnesium nitride was treated with excess water. By passing the emitted gas both through bromine water or through a neutral solution of potassium permanganate, and when it is burned, the same gaseous product is formed. Write the equations of the reactions described.

Chlorine water has the smell of chlorine. When alkalizing, the smell disappears, and when hydrochloric acid is added, it becomes stronger than before. Write the equations of the reactions described.

The solid formed during the heating of malachite was heated in a hydrogen atmosphere. The reaction product was treated with concentrated sulfuric acid and, after separation from sulfuric acid, introduced into the sodium chloride solution containing copper filings, and a precipitate formed. Write the equations of the reactions described.

Phosphine was passed through a hot solution of concentrated nitric acid. The solution was neutralized with quicklime, the precipitated precipitate was separated, mixed with coke and silica and calcined. The reaction product, which glows in air, is heated in a solution of caustic soda. Write the equations of the reactions described.

The iron powder was dissolved in a large amount of dilute sulfuric acid and air was passed through the resulting solution, followed by a gas with the smell of rotten eggs. The resulting insoluble salt was separated and dissolved in a hot solution of concentrated nitric acid. Write the equations of the reactions described.

Colorless gases are emitted when keeping concentrated sulfuric acid with both sodium chloride and sodium iodide. By passing these gases through an aqueous solution of ammonia, salts form. Write the equations of the reactions described.

The magnesium powder was mixed with silicon and heated. The reaction product was treated with cold water and the evolved gas was passed through hot water. The precipitate was separated, mixed with caustic soda and heated to melt. Write the equations of the reactions described.

One of the products of the interaction of ammonia with bromine – a gas that is part of the atmosphere, mixed with hydrogen and heated in the presence of platinum. The resulting gas mixture was passed through a solution of hydrochloric acid and potassium nitrite was added to the resulting solution with slight heating. Write the equations of the reactions described.

The salt obtained by dissolving copper in dilute nitric acid was electrolyzed using graphite electrodes. The substance released at the anode was reacted with sodium, and the resulting reaction product was placed in a vessel with carbon dioxide. Write the equations of the reactions described.

Unknown substance A is dissolved in concentrated hydrochloric acid, the dissolution process is accompanied by the release of gas with the smell of rotten eggs; after neutralization of the solution with alkali, a white (light green) colored precipitate is formed. When baking substance A, two oxides are formed. One of them is a gas that has a characteristic strong smell and bleaches bromine water with the formation of two strong acids in solution. Write the equations of the reactions described.

Magnesium was heated in a vessel filled with ammonia gas. The resulting substance was dissolved in a concentrated solution of hydrobromic acid, the solution was evaporated and the residue was heated until the smell appeared, after which the alkali solution was added. Write the equations of the reactions described.

Soda ash was added to the trivalent chromium sulphate solution. The precipitate separated was separated, transferred to caustic soda solution, bromine added and heated. After neutralizing the reaction products with sulfuric acid, the solution acquires an orange color, which disappears after passing sulfur dioxide through the solution. Write the equations of the reactions described.

Quicklime calcined with an excess of coke. The reaction product after treatment with water is used to absorb sulfur and carbon dioxide. Write the equations of the reactions described.

Ferric sulfide was affected by a solution of hydrochloric acid, the evolved gas was collected and burned in the air. The reaction products were passed through an excess of potassium hydroxide solution, after which a solution of potassium permanganate was added to the resulting solution. Write the equations of the reactions described.

The solid product of thermal decomposition of malachite was dissolved by heating in concentrated nitric acid. The solution was carefully evaporated and the solid residue was calcined to give a black substance, which was heated in an excess of ammonia (gas). Write the equations of the reactions described.

Red phosphorus burned in chlorine atmosphere. The reaction product was treated with excess water and powdered zinc was added to the solution. The evolved gas was passed over heated ferrous oxide. Write the reactions of the described transformations.

The silver-gray metal, which is attracted by a magnet, is introduced into hot concentrated sulfuric acid and heated. The solution was cooled and caustic soda was added until the formation of an amorphous brown precipitate ceased. The precipitate was separated, calcined and dissolved in concentrated hydrochloric acid with heating. Write the equations of the reactions described.

The magnesium chips were heated under a nitrogen atmosphere and the reaction product was successively treated with boiling water, solutions of sulfuric acid and barium nitrate. Write the equations of the reactions described.

The thermal decomposition of salt A in the presence of manganese dioxide resulted in the formation of binary salt B and a gas that supports combustion and is part of the air; when this salt is heated without a catalyst, salt B and the salt of the highest oxygen-containing acid are formed. When salt A interacts with hydrochloric acid, a yellow-green poisonous gas (simple substance) is released and salt B is formed. Salt B colors the flame purple; when it interacts with a solution of silver nitrate, a white precipitate appears. Write the equations of the reactions described.

The precipitate obtained by adding caustic soda to the aluminum sulfate solution was separated, calcined, mixed with soda ash and heated to melt. After treatment of the residue with sulfuric acid, the original aluminum salt was obtained. Write the equations of the reactions described.

The substance formed during the melting of magnesium with silicon was treated with water, as a result a precipitate formed and a colorless gas was released. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate, thus forming two water-insoluble binary substances. Write the equations of the reactions described.

The substance obtained by heating the iron oxide in an atmosphere of hydrogen was added to hot concentrated sulfuric acid and heated. The resulting solution was evaporated, the residue was dissolved in water and treated with a solution of barium chloride. The solution was filtered and a copper plate was added to the filtrate, which dissolved after some time. Write the equations of the reactions described.

Lime “extinguished” water. In the resulting solution missed gas, which is released during the calcination of sodium bicarbonate, while observing the formation and subsequent dissolution of the precipitate. Write the equations of the reactions described.

A mixture of nitrogen and hydrogen was successively passed over heated platinum and through a solution of sulfuric acid. Barium chloride was added to the solution and, after separation of the precipitated precipitate, lime milk and heated. Write the equations of the reactions described.

Give examples of interaction:

two acid salts

two acid oxides

Write the equations of the reactions described.

A solution of medium salt, formed by passing sulfur dioxide through an alkali solution, was left for a long time in air. The solid substance formed after evaporation of the solution was mixed with coke and heated to a high temperature. When hydrochloric acid is added to the solid reaction product, gas with a smell of rotten eggs is released. Write the equations of the reactions described.

A solution of dilute sulfuric acid was added to the black powder and heated. A solution of caustic soda was poured into the resulting blue solution until precipitation stopped. The precipitate was filtered and heated. The reaction product was heated in an atmosphere of hydrogen, resulting in a substance of red color. Write the equations of the reactions described.

Red phosphorus was burned under chlorine and a small amount (a few drops) of water was added to the reaction product. The evolved substance was dissolved in an excess of water, iron powder was added to the resulting solution, and the gaseous reaction product was passed over a copper plate oxidized to oxide of bivalent copper. Write the reactions of the described transformations.

Iron (III) chloride solution was electrolyzed with graphite electrodes. The brown precipitate formed during electrolysis was filtered and dissolved in sodium hydroxide solution, after which the amount of sulfuric acid was added, which is necessary for the formation of a clear solution. The product released at the anode was passed through a hot solution of potassium hydroxide. Write the equations of the reactions described.

Aluminum chloride was added to the solution of crystalline soda, the precipitated precipitate was separated and treated with sodium hydroxide solution. The resulting solution was neutralized with nitric acid, the precipitated precipitate was separated and calcined. Write the equations of the reactions described.

Ammonia was mixed with a large excess of air, heated in the presence of platinum, and after some time was absorbed with water. Copper chips, added to the resulting solution, dissolve with the release of brown gas. Write the equations of the reactions described.

When a solution of acid A is added to manganese dioxide, a poisonous yellow-green gas is released. By passing the released gas through a hot solution of potassium hydroxide, a substance is obtained which is used in the manufacture of matches and some other incendiary compounds. During the thermal decomposition of the latter in the presence of manganese dioxide, a salt is formed, from which the initial acid A can be obtained by reacting with concentrated sulfuric acid, and a colorless gas, which also contains atmospheric air composition. Write the equations of the reactions described.

The product of the interaction of silicon with chlorine is easily hydrolyzed. When fusing solid hydrolysis product with both caustic and soda ash, liquid glass is formed. Write the equations of the reactions described.

To the solution obtained by dissolving iron in hot concentrated hydrochloric acid, added caustic soda. The precipitate separated was separated, left for a long time in air, and then dissolved in dilute hydrochloric acid. Write the equations of the reactions described.

When an orange substance is heated, it decomposes; among decomposition products – colorless gas and solid green. The gas released reacts with lithium even with slight heating. The product of the last reaction interacts with water, and gas with a strong odor is released, which can reduce metals, such as copper, from their oxides. Write the equations of the reactions described.

Gas with the smell of rotten eggs was passed through concentrated sulfuric acid at room temperature. The precipitate was separated and treated with hot concentrated nitric acid; the emitted gas was dissolved in a large amount of water and a piece of copper was added to the resulting solution. Write the reactions of the described transformations.

Salt obtained by dissolving iron in hot concentrated sulfuric acid was treated with excess sodium hydroxide solution. The precipitated brown precipitate was filtered and calcined. The resulting substance is fused with iron. Write the equations of the reactions described.

Metallic zinc was added to the concentrated sulfuric acid. The resulting salt was isolated, dissolved in water, and barium nitrate was added to the solution. After separation of the precipitate, magnesium chips were introduced into the solution, the solution was filtered, the filtrate was evaporated and calcined. Write the equations of the reactions described.

The unknown red substance was heated in chlorine and the reaction product was dissolved in water. Alkali was added to the resulting solution, the precipitated blue precipitate was filtered and calcined. When the calcination product, which is black in color, was heated with coke, the starting material was red. Write the equations of the reactions described.

Iodine was heated with an excess of phosphorus and the reaction product was treated with a small amount of water. The gaseous reaction product was completely neutralized with sodium hydroxide solution and silver nitrate was added to the resulting solution. Write the equations of the reactions described.

Iron burned in chlorine. The reaction product was dissolved in water and iron filings were added to the solution. After some time, the solution was filtered and sodium sulfide was added to the filtrate. The precipitate separated was separated and treated with 20% sulfuric acid to obtain an almost colorless solution. Write the equations of the reactions described.

The gas evolved when heated solid salt with concentrated sulfuric acid, was passed through a solution of potassium permanganate. The gaseous reaction product was absorbed with a cold solution of caustic soda. After adding to the resulting solution of hydroiodic acid, a strong odor appears and the solution becomes dark in color. Write the equations of the reactions described.

Through the solution obtained during the slaking of lime, missed the gas, which is formed upon receipt of quicklime from limestone; the result is a white precipitate. Under the action of acetic acid on the precipitate produced, the same gas is produced, which is formed during calcination of calcium carbonate. Write the equations of the reactions described.

The red substance, which is used in the production of matches, was burned in excess air and the reaction product was dissolved in a large amount of water when heated. After neutralizing the resulting solution with baking soda, silver nitrate was added to it. Write the equations of the reactions described.

Gas escaping from the reaction of hydrochloric acid with potassium permanganate was passed through the sodium bromide solution. After the reaction, the solution was evaporated, the residue was dissolved in water and electrolyzed with graphite electrodes. The gaseous reaction products were mixed with each other and lit up, and an explosion occurred as a result. Write the equations of the reactions described.

The gas formed during the combustion of coke, for a long time in contact with red-hot coal. The reaction product was successively passed through a layer of heated iron ore and burnt lime. Write the equations of the reactions described.

Copper shavings were added to the heated concentrated sulfuric acid and the evolved gas was passed through a solution of caustic soda (excess). The reaction product was isolated, dissolved in water and heated with sulfur, which dissolved as a result of the reaction. To the resulting solution was added diluted sulfuric acid. Write the equations of the reactions described.

Hydrochloric acid was added to the solutions of substances L and B, which paint the flame yellow, when a solution of substance A interacts with hydrochloric acid, a colorless gas with an unpleasant odor is released, which forms a black precipitate when lead (II) nitrate is passed through. When a solution of substance B with hydrochloric acid is heated, the solution changes from yellow to green and a poisonous yellow-green gas with a characteristic strong odor is released. When barium nitrate is added to the solution of substance B, a yellow color precipitates. Write the equations of the reactions described.

To the pyrolusite, a hydrochloric acid solution was carefully added and the released gas was passed into a beaker, half filled with a cold solution of potassium hydroxide. After the reaction, the glass was covered with a cardboard and left, while the glass was illuminated by the sun’s rays; after some time a smoldering torch was brought into the glass, which flashed brightly. Write the equations of the reactions described.

The precipitate obtained by the interaction of a solution of aluminum salt and alkali, calcined. The reaction product was dissolved in a concentrated hot alkali solution. Carbon dioxide was passed through the resulting solution, as a result of which a precipitate formed. Write the equations of the transformations described.

Black powder, which was formed by prolonged heating of the red metal in excess of air, was dissolved in 10% sulfuric acid and a blue solution was obtained. Alkali was added to the solution and the precipitated precipitate was separated and dissolved in an excess of ammonia solution. Write the equations of the reactions described.

Phosphorus was added to the solid, which is formed when phosphorus is burned in excess of chlorine, and the mixture is heated. The reaction product was treated with a small amount of hot water, and a solution of potassium permanganate acidified with sulfuric acid was added to the resulting solution. Write the equations of the reactions described.

Carbon dioxide was passed through barite water. Barium hydroxide was added to the resulting solution, the reaction product was separated and dissolved in phosphoric acid. Write the equations of the reactions described.

Zinc nitrate was calcined, the reaction product was heated with a solution of sodium hydroxide when heated. Carbon dioxide was passed through the resulting solution until precipitation stopped, and then treated with an excess of concentrated ammonia, and the precipitate dissolved. Write the equations of the reactions described.

In two vessels are solutions of unknown substances. When the first substance of barium chloride is added to the solution, a white precipitate is formed which is insoluble in water and acids. A white precipitate is also produced when silver nitrate solution is added to the sample taken from the second vessel. When heated, samples of the first solution with sodium hydroxide gas emit a strong smell. When the second solution interacts with sodium chromate, a yellow color precipitates. Write the equations of the reactions described.

Sulfur dioxide was dissolved in water and the solution was neutralized by adding caustic soda. Hydrogen peroxide was added to the resulting solution, and after the end of the reaction sulfuric acid was added. Write the equations of the reactions described.

Zinc was dissolved in a very dilute nitric acid, the resulting solution was carefully evaporated and the residue was calcined. The reaction products were mixed with coke and heated. Make the equations of reactions of the described transformations.

Substances released at the cathode and anode during the electrolysis of sodium iodide solution with graphite electrodes react with each other. The reaction product interacts with concentrated sulfuric acid to produce a gas that is passed through a solution of potassium hydroxide. Write the equations of the reactions described.

The substance, which is formed during the electrolysis of the melt of bauxite in cryolite, dissolves both in hydrochloric acid solution and in alkali solution with the release of the same gas. When mixing the resulting solutions, a voluminous white precipitate is formed. Write the equations of the reactions described.

Concentrated hydrochloric acid was added to lead (IV) oxide with heating. The evolved gas was passed through a heated solution of caustic potash. The solution was cooled, the salt of oxygen-containing acid was filtered and dried. When the obtained salt is heated with hydrochloric acid, a poisonous gas is released, and when heated in the presence of manganese dioxide, the gas entering the composition of the atmosphere. Write the equations of the reactions described.

The brown precipitate obtained by the interaction of sodium sulfite with an aqueous solution of potassium permanganate was filtered and treated with concentrated sulfuric acid. The released gas reacts with aluminum when heated, and the resulting substance with hydrochloric acid solution. Write the reactions of the described transformations.

Calcium is heated in a hydrogen atmosphere. The reaction product was treated with water, the evolved gas was passed over the heated zinc oxide, and soda ash was added to the solution. Write the equations of the reactions described.

Silver nitrate was calcined and the solid reaction product was heated in oxygen. The resulting substance is dissolved in an excess of concentrated ammonia. When passing through the resulting solution of hydrogen sulfide, a black precipitate is formed. Write the equations of the reactions described.

The solid substance that is formed when the phosphorus and phosphorus pentachloride is heated is dissolved in a large amount of water. Part of the solution obtained was added to a potassium permanganate solution acidified with sulfuric acid, while the latter was discolored. Write the equations of the reactions described.

What is Sulfa

Several zinc granules were introduced into a vessel with concentrated sulfuric acid. The evolved gas was passed through a solution of lead (II) acetate, the precipitate was separated, fired, and the resulting gas was introduced into contact with an aqueous solution of potassium permanganate. Write the equations of the reactions described.

Several zinc granules were dissolved by heating in caustic soda solution. Nitric acid was added to the resulting solution in small portions until a precipitate formed. The precipitate was separated, dissolved in dilute nitric acid, the solution was carefully evaporated and the residue was calcined. Write the equations of the reactions described.

The gas released during the dissolution of copper in hot concentrated nitric acid, can interact with the gas released during the processing of copper with hot concentrated sulfuric acid, and copper. Write the equations of the reactions described.

Iron (III) chloride solution was electrolyzed with graphite electrodes. The precipitated brown precipitate (a by-product of electrolysis) was filtered, calcined and fused with a substance formed on the cathode. Another, also released at the cathode, was reacted with the product released during the electrolysis at the anode; the reaction takes place under lighting and with an explosion. Write the equations of the reactions described.

White water insoluble salt that is meetingGonaturally occurring in the form of a mineral widely used in construction and architecture, calcined at 1000 ° C. After cooling, water was added to the solid residue and a gaseous decomposition reaction product was passed through the resulting solution, as a result a white precipitate formed, which dissolved upon further passage of gas. Write the equations of the reactions described.

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