A10. Chemical properties of hydroxides and acids

substances are given: potassium dichromate, concentrated sulfuric acid and potassium hydroxide, sodium carbonate.

1. There is a serious error in Audrey's answer.
   So I'll write it right
   1.H2SO4+2KOH---gt; K2SO4 + 2H2O
   2. K2Cr2O7 + 4H2SO4 ---gt; K2SO4 + Cr2(SO4)3 + 4H2O + 3O2
   3. Na2CO3 + H2SO4 ---gt; Na2SO4 + CO2 + H2O
   4. Na2CO3 + KOH lt;--gt; K2CO3 + NaOH (potassium is a more active metal than sodium, so there is a substitution reaction)
2. The reaction between Na2CO3 and KOH is possible only with an excess of alkali...)
   Alkali + salt = (new) base + (new) salt. But! The starting materials must be in solution, and at least one of the reaction products must precipitate or dissolve little.
   It looks like this:
   Na2CO3 + 2 KOH = 2 NaOH + K2CO3.

   Baby Roo is right.
   Audrey is right too.

3. 1.H2SO4 + 2KOH --gt; K2SO4 + 2H2O
   2.K2Cr2O7 + 4 H2SO4 --gt; K2SO4 + Cr2(SO4)3 + 4 H2O + 3O
   3. Na2CO3 + H2SO4 --gt; Na2SO4 + CO2 + H2O
   4. Na2CO3 + KOH --gt; no reaction
4. There is a serious error in the Sage's answer.
   Therefore, I will write correctly:
   4. Na2CO3 + 2 KOH = 2 NaOH + K2CO3.

   Audrey wrote only that there is no reaction between Na2CO3 and KOH... .

In total, there are three classes of inorganic compounds in nature: salts, oxides and hydroxides. Also, substances such as CI2, І2 and the like, consisting of only one chemical element, are distinguished into a separate class.

Classification of hydroxides

It is one of three existing classes of inorganic compounds. They are divided into acids, bases and amphoteric substances. The former consist of an H+ cation and an anion in the form of an acidic residue, for example, CI-. The structure of the second includes a cation of a metal, for example, Ca +, as well as an anion in the form of a hydroxyl group OH-. The latter are characterized by the fact that they simultaneously possess the chemical properties inherent in acids and bases. Such hydroxides include compounds of aluminum and iron. Bases, like other inorganic substances, can be divided into groups depending on their reactivity. The strongest in this regard are potassium and sodium hydroxide, which are also called alkalis. They quickly react with various substances.

Physical properties

This substance under normal conditions (at room temperature and low pressure) is in a solid state of aggregation. It looks like small crystals that are colorless and odorless, highly soluble in water. These crystals are extremely hygroscopic. Staying in the open air for a long time, they blur and turn into a solution, absorbing moisture from the atmosphere. The same phenomenon is observed with sodium hydroxide, the hygroscopicity of which is even higher.

Other names for potassium hydroxide

In common speech, this substance is called caustic potash, as well as caustic potash and potassium lye.

Chemical properties

The substance in question has all the features that are characteristic of bases. Its alkaline properties are very pronounced, like that of sodium hydroxide. When potassium hydroxide is burned, oxide of this metal and water are released. K2O has a light yellow color.

Salt interaction

Salts - substances consisting of a cation of a metal and an anion, represented by an acid residue. They are formed mainly by the interaction of active metals with acids. A substitution reaction occurs, in which, in addition to the salt, hydrogen is formed, which is released as a gas. When reacting with substances of this class, another salt containing potassium is formed, as well as a hydroxide of a metal. For example, when this substance interacts with copper chloride, copper hydroxide and potassium chloride are formed, which precipitate. In order to carry out this kind of reaction, it is necessary to take alkali and copper chloride in such proportions that two molecules of the first substance account for one second, that is, the ratio of the obtained substances will be as follows: for one molecule of cuprum hydroxide, two potassium chlorides. Such interactions are called exchange reactions. In order for them to be carried out, the following conditions must be met: one of the interaction products must either precipitate, or evaporate in the form of a gas, or become water. The metal that is part of the salt should be less reactive than potassium (everything except lithium).

Reactions with acids

All bases, including potassium hydroxide, are able to interact with acids. The most common and frequently used reaction is that involving the substance in question and sulfuric acid. In this case, potassium hydroxide is needed in such an amount that there are two of this compound per molecule of acid. In this kind of reaction, substances such as potassium sulfate and water are formed in a molar ratio of one to two. A similar chemical process is actively used in industry, since the resulting product is widely used everywhere.

What happens if you add it to the oxide?

In this case, in fact, an exchange reaction will also occur. For example, if you mix potassium hydroxide and iron dioxide in a molar ratio of two to one, you can get ferum hydroxide (II), which precipitates into a dark green precipitate, as well as potassium oxide in such proportions that one molecule of the first substance will have one second .

The main methods for producing potassium hydroxide

In industry, most often it is mined by electrolysis of a solution of potassium chloride. Obtaining potassium hydroxide is a process in which, in addition to the extracted substance, H 2 and CI 2 are formed.

Industrial use

Basically, this substance is used in the manufacture of soap and other cleaning products. This process uses the reaction of the compound in question with some kind of fat. Sodium hydroxide can also be used for the same purpose. Also considered in this article, the substance is widely used in the chemical industry to obtain a variety of potassium compounds, primarily its sulfate.

The reaction in which it is formed was discussed by us above. In the same field, it is used as a compound that absorbs gases such as hydrogen sulfide, sulfur dioxide, carbon dioxide. It also acts as a desiccant due to its high hygroscopic properties. It can be used to determine the concentration level of acids in a solution. In addition, hydroxide is also used in the food industry. Here it is used as a food additive E525. It acts as an acidity regulator. You can meet it in the composition of cocoa, chocolate and other similar products. Potassium hydroxide is used in the processing of cellulose, to obtain viscose, used in alkaline batteries, added to dishwashing detergents or cleaning various surfaces, to treat cotton fabric and make it more hygroscopic.

Potassium compounds derived from its hydroxide and their uses

Most often, the substance in question is used to extract potassium sulfate, which is used as a fertilizer. They feed the plants during the growing season. It is also used as an emulsifier in the food industry - it makes it possible to obtain a homogeneous mass, consisting of components that do not mix under normal conditions. For its designation, the marking E515 is used. It can also, like potassium hydroxide, act as an acidity regulator. Sulfate is often used as a salt substitute. In addition, this substance finds its application in pharmacology in the production of dietary supplements, as well as in the manufacture of dyes. In addition, it is also used in the glass industry.

Potassium hydroxide and the human body

In the form of a concentrated solution, this chemical compound is dangerous to living organisms. Contact with skin or mucous membranes can cause serious injury. A concentrated solution of potassium hydroxide causes more severe burns than acids. It is also able to dissolve many organic compounds. This substance belongs to the second hazard class, that is, when working with it, special rules must be observed. An excess amount of potassium hydroxide in the body leads to the emergence of new skin diseases or exacerbation of chronic ones.

"Sulfuric acid lesson" - What are the general properties of acids characteristic of sulfuric acid? Lesson motto: How does concentrated sulfuric acid interact with organic compounds? Acid rain. Negative impact on the environment. "How does dilute sulfuric acid interact with metals? What oxidation states are characteristic of a sulfur atom?

"Sulfuric acid" - Nickel sulfate. S+6O3 is a colorless liquid. Anoxic acids. The interaction of acid with sucrose. concentrated sulfuric acid. polybasic acids. Dilute sulfuric acid exhibits all the characteristic properties of acids. Sulfuric acid. There has long been a strict rule regarding the mixing of sulfuric acid with water.

"Metal copper" - The role of bronze was especially great. The simple substance copper is a beautiful pinkish-red ductile metal. The chemical element of the secondary subgroup of group 1 is Cu (Copper). In total, the body of an average person (body weight 70 kg) contains 72 mg of copper. The main role of copper in plant and animal tissues is participation in enzymatic catalysis.

"Obtaining sulfuric acid" - stage II - obtaining SO3. Barium chloride is a quality reagent for H2SO4. Findings. The purpose of the lesson. Stage I - production of sulfur dioxide SO2. H2SO4 conc Oxidation product. 3rd stage. H2SO4 dil. concentrated sulfuric acid. Chemical properties and production of sulfuric acid in industry. Acid is an oxidizing agent.

"Acid Grade 8" - What kind of acid is used to make drawings on glass? Describe oxides. What acid is found in mineral water? What class of chemicals will we study? What acid is found in gastric juice? From what class of substances can an acid be obtained? Recall what we know about acids with an example.

"Sulfuric acid" - It is necessary to rinse the mouth and throat with a solution of soda (20 grams of baking soda per 1 liter of water). The lethal dose of sulfuric acid when ingested is 5 milligrams. After particularly strong volcanic eruptions, significant climate changes can occur. The damaging effects of sulfuric acid, methods of protection.

Characteristic chemical properties of bases, and amphoteric hydroxides. Characteristic chemical

acid properties.

1. Potassium hydroxide interacts with each of the two substances

1) NH 3 and HCl 2) CO 2 and CuCl 2 3) H 2 SO 4 and NaNO 3 4) MgO and HNO 3

2. Dilute hydrochloric acid reacts with each of the two substances

1) copper and sodium hydroxide

2) magnesium and silver nitrate

3) iron and silicon oxide (IV)

4) lead and potassium nitrate

3. Interacts with hydrochloric acid

1) NaHCO 3 2) Hg 3) SiO 2 4) S

4. Neutralization reaction occurs when interacting

1) Fe 2 O 3 and HCl

2) Fe (OH) 3 and HCl

3) FeCl 3 and NaNCS

5. Iron hydroxide (II) interacts with

1) nitric acid

2) calcium oxide

3) copper sulfate

4) ammonia

6. Dilute sulfuric acid does not react with

1) calcium hydroxide

2) copper oxide (II)

4) carbon monoxide (IV)

7. Each of the two substances reacts with potassium hydroxide

1) AlCl 3 and H 2 S

2) CuO and Ba (OH) 2

3) CaCO 3 and NH 3

4) K 2 SO 4 and AlCl 3

8. Calcium hydroxide reacts with each of the two substances

1) HCl and CO 2

4) BaCl 2 and NaOH

9. Potassium hydroxide reacts with

2) alkali

3) acid

4) acid and alkali

10. Calcium hydroxide does not interact

1) HCl 2) ZnS 3) CO 2 4) HNO 3

11. Chromium (III) hydroxide reacts with each of the two substances

1) CO 2 and HCl

2) SiO 2 and Cu (OH) 2

4) H 2 SO 4 and NaOH

12. Neutralization reaction occurs between

thirteen . Each of the two substances interacts with a solution of sulfuric acid:

14. Calcium hydroxide reacts with

15. Concentrated nitric acid under normal conditions does not interact with

16. When draining aqueous solutions of acetic acid and potassium hydroxide, a

17. Sodium hydroxide does not react with

1)

Al(OH)3

2)

ZnO

3)

H2SO4

4)

Ba(OH)2

18. Dilute sulfuric acid reacts with each of the two substances:

1)	Na 2 SiO 3 and HNO 3
2)	Fe 2 O 3 and KNO 3
3)	Ag and Cu(OH) 2
4)	Fe and Al 2 O 3

19. Both aluminum hydroxide and hydrochloric acid can interact with

1)

CuO

2)

H2SO4

3)

CO2

4)

NaOH

20. Hydrochloric acid does not interact with any of the two substances:

21. With each of the listed substances: H 2 S, KOH, Zn

interacts

1)

Pb(NO 3) 2

2)

ZnSO4

3)

Na2CO3

4)

HCl

22. Dilute sulfuric acid can react with each of two substances:

23. Each of the two substances interacts with a solution of sulfuric acid:

24. Concentrated nitric acid under normal conditions does not interact with

25. A solution of sodium hydroxide reacts with each of the substances indicated in pairs

26. Sodium hydroxide does not react with

1)

Al(OH)3

2)

ZnO

3)

H2SO4

4)

Ba(OH)2

27. Dilute sulfuric acid reacts with each of two substances:

1)	Na 2 SiO 3 and HNO 3
2)	Fe 2 O 3 and KNO 3
3)	Ag and Cu(OH) 2
4)	Fe and Al 2 O 3

28. Both aluminum hydroxide and hydrochloric acid can interact with

1)

CuO

2)

H2SO4

3)

CO2

4)

NaOH

29. Hydrochloric acid does not interact with any of the two substances:

30. Sodium hydroxide solution does not interact with

1)

CO 2

2)

HCl

3)

SO2

4)

MgO

31. Zinc hydroxide interacts with each of the two substances

2) HNO 3 and NaCl

3) Mg (OH) 2 and NaNO 3

4) H 2 S and Fe (OH) 2

ANSWERS: 1-2, 2-2, 3-1, 4-2, 5-1, 6-4, 7-1, 8-1, 9-3, 10-2, 11-4, 12-3, 13-2, 14-4, 15-1, 16-3, 17-4, 18-4, 19-4, 20-3, 21-1, 22-4, 23-2, 24-3, 25- 3, 26-4, 27-4, 28-4, 29-3, 30-4, 31-1.