Sodium hydroxide, characteristics, properties and production, chemical reactions

Sodium hydroxide, characteristics, properties and production, and chemical reactions.

 

 

Sodium hydroxide is an inorganic substance and has chemical formula NaOH.

 

Brief description of the sodium hydroxide

Modification of sodium hydroxide

Physical properties of sodium hydroxide

Obtaining sodium hydroxide

Chemical properties of sodium hydroxide

Chemical reaction of sodium hydroxide

The application and use of sodium hydroxide

 


Brief description of sodium hydroxide:

Sodium hydroxide is an inorganic substance of white color.

The chemical formula of sodium hydroxide Paon.

Has high hygroscopicity. On the air “spreads”, actively absorbing water vapor from the air.

Highly soluble in water, while releasing large amounts of thermal energy. Solution of sodium hydroxide is soapy to the touch.

Sodium hydroxide – the most common alkali. Per year the world produces and consumes about 57 million tons of caustic soda.

Sodium hydroxide corrosive, toxic and corrosive substance. It refers to the substances of the second class of danger. So working with them requires caution. After contact with skin, mucous membranes and eyes are serious chemical burns.

 

Modification of sodium hydroxide:

To 299 OS sodium hydroxide has a stable rhombic modification (a = 0,33994 nm, c = 1,1377 nm) above 299 OS – monoclinic.

 

Physical properties of sodium hydroxide:

Parameter name: Value:
Chemical formula Paon
Synonyms and foreign language names sodium hydroxide (eng.)

caustic soda (Rus.)

sodium hydroxide (Rus.)

caustic soda (Rus.)

The type of substance. inorganic
Appearance colorless rhombic crystals
Color white, colorless
Taste —*
The smell
Aggregate state (at 20 °C and atmospheric pressure of 1 ATM.) solid
Density (state of matter – solid, at 20 °C), kg/m3 2130
Density (state of matter – solid, at 20 °C) g/cm3 2,13
Boiling point, °C 1403
Melting point, °C 323
Hygroscopicity high water absorption
Molar mass, g/mol 39,997

* Note:

— no data.

 

Obtaining sodium hydroxide:

Sodium hydroxide is obtained by the following chemical reactions:

1. of sodium oxide (so-called pyrolytic method):

Pyrolytic method of obtaining sodium hydroxide is the oldest and starts with obtaining of sodium oxide Na2O by calcination of sodium carbonate at a temperature of 1000 °C or heated to 200 °C of the sodium bicarbonate to produce sodium carbonate:

Na2CO3 → Na2O + CO2 (t = 1000 oC),

2NaHCO3 → Na2CO3 + CO2 + H2O (t = 200 oC), followed by the first chemical reaction.

The resulting sodium oxide was cooled and carefully (the reaction occurs with a large amount of heat) added to the water:

Na2O + H2O → 2NaOH.

2. by reacting sodium carbonate solution with slaked lime (ie lime method, caustification soda):

Na2CO3 + Ca(OH)2 → CaCO3 + 2NaOH (t = 80 oC).

The calcium carbonate is separated from the solution by filtration, then the solution uvarivaetsja to obtain a molten product containing about 92 % by weight. NaOH.

3. ferritic method:

Fe2O3 + Na2CO3 → 2NaFeO2 + CO2 (t = 1100-1200 oC).

The reaction mixture is sintered.

2NaFeO2 + (n+1)H2O → Fe2O3•nH2O + 2NaOH.

The reaction proceeds slowly.

Fe2O3•nH2O precipitates, which after separation from the solution is returned to the process in the first reaction.

4. electrolysis:

2NaCl + 2H2O → 2Na2O + H2 + Cl2.

Obtained at the same time also hydrogen and chlorine.

Sodium hydroxide, hydrogen and chlorine are produced by three electrochemical methods. Two of them – electrolysis with solid cathode (diaphragm and membrane methods), the third – electrolysis with a liquid mercury cathode (mercury method).

 

Chemical properties of sodium hydroxide. Chemical reaction of sodium hydroxide:

Sodium hydroxide is a chemically active substance, a strong chemical base.

Aqueous solutions of NaOH have a strong alkaline reaction (pH of 1% solution = 13,4).

Chemical properties of sodium hydroxide are similar to the properties of the hydroxides of other alkali metals. So it is characterized by the following chemical reactions:

1. the reaction of sodium hydroxide with sulfur:

3S + 6NaOH → 2Na2S + Na2SO3 + 3H2O (t = 50-60 °C).

The reaction produces sodium sulfide, sodium sulfite and water. The sodium hydroxide as a starting material is used in the form of a dilute solution.

2. the reaction of sodium hydroxide with chlorine:

2NaOH + Cl2 → NaCl + NaClO + H2O.

The reaction produces sodium chloride, sodium hypochlorite and water. The sodium hydroxide as a starting material is used in the form of a cold dilute solution.

Similar are the reactions of sodium hydroxide and with other Halogens.

3. the reaction of sodium hydroxide with aluminum:

2Al + 6NaOH → 2NaAlO2 + 3H2 + 2Na2O (t = 450 °C).

The reaction produces sodium aluminate, hydrogen and sodium oxide.

4. the reaction of sodium hydroxide with aluminum and water:

2Al + 2NaOH + 6H2O → 2Na[Al(OH)4] + 3H2.

The reaction formed tetrahydroaluminate sodium and hydrogen. The sodium hydroxide as a starting material is used in the form of a concentrated solution.

This reaction was used in the first half of the twentieth century in Aeronautics: for filling hydrogen balloons and airships in the field, because this reaction does not require sources of electricity, and the source reagents can be transported easily.

5. the reaction of sodium hydroxide with zinc:

Zn + 2NaOH → Na2ZnO2 + H2 (t = 550 °C).

The reaction formed zincate sodium and hydrogen.

6. the reaction of sodium hydroxide with zinc and water:

Zn + 2NaOH + 2H2O → Na2[Zn(OH)4] + H2.

The reaction formed tetrahydrozoline sodium and hydrogen. The sodium hydroxide as a starting material is used in the form of a concentrated solution.

7. the reaction of sodium hydroxide with phosphoric acid:

H3PO4 + NaOH → NaH2PO4 + H2O.

The reaction formed digidrogenfosfat of sodium and water. With this as starting materials are used: phosphoric acid in concentrated solution, the sodium hydroxide in the form of a dilute solution.

8. the reaction of sodium hydroxide with nitric acid:

NaOH + HNO3 → NaNO3 + H2O.

The reaction produces sodium nitrate and water. Thus nitric acid as a starting material is used in the form of a dilute solution.

9. the reaction of sodium hydroxide with nitric acid:

NaOH + HNO3 → NaNO3 + H2O.

The reaction produces sodium nitrate and water. Thus nitric acid as a starting material is used in the form of a dilute solution.

Similar are the reactions of sodium hydroxide and other acids.

10. the reaction of sodium hydroxide with hydrogen sulfide:

H2S + 2NaOH → Na2S + 2H2O

H2S + NaOH → NaHS + H2O.

As a result of reaction formed in the first case, the sodium sulfide and water, the second sodium hydrogen sulfide and water. The sodium hydroxide in the first case as the initial substance used in the form of concentrated solution, in the second case – in the form of a dilute solution.

11. the reaction of sodium hydroxide with hydrogen fluoride:

HF + NaOH → NaF + H2O

2HF + NaOH → NaHF2 + H2O.

As a result of reaction formed in the first case, sodium fluoride and water, the second hydrofloric sodium and water. The sodium hydroxide and hydrogen fluoride in the first case as initial substance are used in the form of dilute solution, in the second case, the hydrogen fluoride used in the form of in the form of a concentrated solution.

12. the reaction of sodium hydroxide with bromovalerate:

HBr + NaOH → NaBr + H2O.

The reaction produces bromide of sodium and water. The sodium hydroxide and bromovalerate as initial substance are used in the form of a dilute solution.

13. the reaction of sodium hydroxide with yodovidona:

HI + NaOH → NaI + H2O.

The reaction formed sodium iodide and water. The sodium hydroxide as a starting material is used in the form of a dilute solution.

14. the reaction of sodium hydroxide with zinc oxide:

ZnO + 2NaOH → Na2ZnO2 + H2O (t = 500-600 °C).

Zinc oxide is amphoteric oxide. The reaction formed zincate sodium and water.

15. the reaction of sodium hydroxide with zinc oxide and water:

ZnO + NaOH + H2O → Na[Zn(OH)3] (t = 100 °C),

ZnO + 2NaOH + H2O → Na2[Zn(OH)4] (t = 90 °C).

Oxide of zinc is amphoteric oxide. The reaction produced in the first case, trihydroxide of sodium and water, in the second case, tetrahydrozoline sodium. The sodium hydroxide as a starting material is used in the first case, in the form of a 40 % diluted solution, the second – in the form of a 60% diluted solution.

16. the reaction of sodium hydroxide with aluminum oxide:

Al2O3 + 2NaOH → 2NaAlO2 + H2O (t = 900-1100 °C).

Aluminium oxide is an amphoteric oxide. The reaction produces sodium aluminate and water.

17. the reaction of sodium hydroxide with aluminum oxide and water:

Al2O3 + 6NaOH + 3H2O → 2Na3[Al(OH)6],

Al2O3 + 2NaOH + 3H2O → 2Na[Al(OH)4].

Aluminium oxide is an amphoteric oxide. The reaction produced in the first case, hexahydroxoantimonate sodium, in the second case – tetrahydroaluminate sodium. The sodium hydroxide as a starting material is used in the second case, in the form of a concentrated hot solution.

18. the reaction of sodium hydroxide with iron oxide:

Fe2O3 + 2NaOH → 2NaFeO2 + H2O (t = 600 °C, p).

Iron oxide is an amphoteric oxide. In the reaction, the formed ferrite sodium and water. Reaction occurs by fusion of the starting materials.

Similar are the reactions of sodium hydroxide and other amphoteric oxides.

19. the reaction of sodium hydroxide with carbon dioxide (carbon dioxide):

NaOH + CO2 → NaHCO3.

The reaction produced sodium bicarbonate.

20. the reaction of sodium hydroxide with sulfur dioxide:

SO2 + NaOH → NaHSO3.

The reaction produced sodium Hydrosulphite. The sodium hydroxide as a starting material is used in the form of a dilute solution.

21. the reaction of sodium hydroxide with silicon oxide:

2NaOH + SiO2 → Na2SiO3 + H2O (t = 900-1000 °C),

4NaOH + SiO2 → Na4SiO4 + 2H2O.

The reaction produced in the first case, sodium silicate and water, in the second case, the orthosilicate of sodium and water. The sodium hydroxide as a starting material is used in the second case, in the form of a concentrated solution.

22. the reaction of sodium hydroxide with aluminium hydroxide:

Al(OH)3 + NaOH → NaAlO2 + 2H2O (t = 1000 °C),

Al(OH)3 + NaOH → Na[Al(OH)4].

Aluminium hydroxide is an amphoteric base. As a result of reaction formed in the first case, sodium aluminate and water, in the second case – tetrahydroaluminate sodium. The sodium hydroxide as a starting material is used in the second case, in the form of a concentrated solution.

23. the reaction of sodium hydroxide with zinc hydroxide:

Zn(OH)2 + 2NaOH → Na2[Zn(OH)4].

Zinc hydroxide is an amphoteric base. The reaction formed tetrahydrozoline sodium. The sodium hydroxide as a starting material is used in the form of a concentrated solution.

24. the reaction of sodium hydroxide with iron hydroxide:

Fe(OH)3 + 3NaOH ⇄ Na3[Fe(OH)6].

The iron hydroxide is an amphoteric base. The reaction produces sodium hexahydroxoplatinate.

Similar are the reactions of sodium hydroxide and other amphoteric hydroxides.

25. the reaction of sodium hydroxide with iron sulfate:

FeSO4 + 2NaOH → Fe(OH)2 + Na2SO4 (kat = N2).

In the reaction, the formed hydroxide iron and sodium sulfate.

26. the reaction of sodium hydroxide with copper chloride:

CuCl2 + 2NaOH → Cu(OH)2 + 2NaCl.

The reaction produces hydroxide copper and sodium chloride. The sodium hydroxide as a starting material is used in the form of a dilute solution.

27. the reaction of sodium hydroxide with lead nitrate:

Pb(NO3)2 + 2NaOH → Pb(OH)2 + 2NaNO3.

The reaction produces lead hydroxide and sodium nitrate. The sodium hydroxide as a starting material is used in the form of a dilute solution.

28. the reaction of sodium hydroxide with aluminum chloride:

AlCl3 + 3NaOH → Al(OH)3 + 3NaCl.

In the reaction, the formed hydroxide of aluminium and sodium chloride. The sodium hydroxide as a starting material is used in the form of a dilute solution.

Similar are the reactions of sodium hydroxide and other salts.

 

The application and use of sodium hydroxide:

Sodium hydroxide is used in many industries and for domestic purposes:

in the pulp and paper industry for delignification(sulfate process) pulp, production of paper, cardboard, synthetic fibers, wood-fiber boards;

for the saponification of fats in the manufacture of soap, shampoo and other detergents;

– in the chemical industries to neutralize acids and acidic oxides, as a reagent or catalyst in chemical reactions, in chemical analysis for the titration, for etching aluminum and in the production of pure metals in oil refining for the production of oils;

– for the production of biodiesel fuel – derived from vegetable oils and used to replace the conventional diesel fuel.

To obtain biodiesel by nine mass units of vegetable oil added to one mass unit of alcohol (ie, observed ratio 9:1) and alkaline catalyst (NaOH). The resulting ether (mainly linoleic acid) has good Flammability, provide a high cetane number. Cetane number – the conditional quantitative characteristic of samovosplameneniem of disainikeele in the cylinder (similar to octane number for gasoline). If the mineral diesel fuel characteristic figure in 50-52 %, the methyl ester is initially corresponds to 56-58 % cetena. Raw materials for biodiesel production may be different vegetable oils: rapeseed, soybean, and others, except those in which a high content of palmitic acid (palm oil). For its production in the esterification process also produces glycerine which is used in the food, cosmetic and paper industry;

– as an agent for dissolving blockages of sewer pipes in the form of dry granules or in the composition of the gels. Sodium hydroxide disaggregates the blockage and helps promote it further through the pipe;

in the textile industry for mercerizing cotton and wool. Short-term treatment with caustic soda followed by washing the fiber gains strength and silky luster;

– in cooking: for washing and cleaning fruit and vegetables from the skin, in the manufacture of chocolate and cocoa drinks, ice cream, caramel colouring, to soften the olives and give them a black color, the production of bakery products. Registered as a food additive E-524;

– in photography – as the accelerating substance in developers for high-speed processing of photographic materials.

 

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