Oxidation state +1.
Sodium compounds have been known since ancient times. Sodium chloride is an essential component of human food.
C it is read that man began to use it in the Neolithic, i.e. about 5-7 thousand years ago.The Old Testament mentions a certain substance called "neter". This substance was used as a detergent. Most likely, neter is soda, sodium carbonate, which was formed in the salty Egyptian lakes with calcareous shores. The Greek authors Aristotle and Dioscorides later wrote about the same substance, but under the name "nitron", and the ancient Roman historian Pliny the Elder, referring to the same substance, called it "nitrum".
In the 18th century. many different sodium compounds were already known to chemists. Sodium salts were widely used in medicine, leather dressing, and fabric dyeing.
Metallic sodium was first obtained by the English chemist and physicist Humphrey Davy by electrolysis of molten sodium hydroxide (using a voltaic column of 250 pairs of copper and zinc plates). Name "
sodium "Davy's choice for this element reflects its origin from soda Na 2 CO 3. The Latin and Russian names for the element are derived from the Arabic natrun (natural soda).Distribution of sodium in nature and its industrial extraction. Sodium is the seventh most abundant element and the fifth most abundant metal (after aluminum, iron, calcium, and magnesium). Its content in the earth's crust is 2.27%. Most of the sodium is found in various aluminosilicates.Huge deposits of sodium salts in relatively pure form exist on all continents. They are the result of the evaporation of ancient seas. This process is still ongoing in Salt Lake, Utah, the Dead Sea and elsewhere. Sodium occurs as chloride
NaCl (halite, rock salt), as well as carbonate Na 2 CO 3 NaHCO 3 2 H 2 O (throne), nitrate NaNO 3 (saltpeter), sulfate Na 2 SO 4 10 H 2 O (mirabilite), tetraborate Na 2 B 4 O 7 10 H 2 O (borax) and Na 2 B 4 O 7 4 H 2 O (kernite) and other salts.Inexhaustible reserves of sodium chloride are found in natural brines and ocean waters (about 30 kg m –3). It is estimated that rock salt in an amount equivalent to the content of sodium chloride in the World Ocean would occupy a volume of 19 million cubic meters. km (50% more than the total volume of the North American continent above sea level). A prism of this volume with a base area of 1 sq. km can reach the moon 47 times.
Now the total production of sodium chloride from seawater has reached 6-7 million tons per year, which is about a third of the total world production.
Living matter contains on average 0.02% sodium; in animals it is more than in plants.
Characterization of a simple substance and industrial production of metallic sodium. Sodium is a silvery-white metal, in thin layers with a violet tint, plastic, even soft (easily cut with a knife), a fresh cut of sodium glistens. The electrical conductivity and thermal conductivity of sodium are quite high, the density is 0.96842 g / cm 3 (at 19.7 ° C), the melting point is 97.86 ° C, and the boiling point is 883.15 ° C.The ternary alloy, containing 12% sodium, 47% potassium and 41% cesium, has the lowest melting point for metallic systems, equal to –78 ° C.
Sodium and its compounds color the flame bright yellow. The double line in the sodium spectrum corresponds to transition 3
s 1 –3 p 1 in the atoms of the element.The reactivity of sodium is high. In air, it quickly becomes covered with a film of a mixture of peroxide, hydroxide and carbonate. Sodium burns in oxygen, fluorine and chlorine. When metal is burned in air, peroxide is formed
Na 2 O 2 (with an admixture of oxide Na 2 O ).Sodium reacts with sulfur already when rubbed in a mortar, and reduces sulfuric acid to sulfur or even to sulfide. Solid carbon dioxide ("dry ice") explodes on contact with sodium (carbon dioxide fire extinguishers cannot be used to extinguish burning sodium!). With nitrogen, the reaction takes place only in an electric discharge. Sodium does not interact only with inert gases.
Sodium reacts actively with water:
Na + 2 H 2 O = 2 NaOH + H 2The heat generated during the reaction is sufficient to melt the metal. Therefore, if a small piece of sodium is thrown into water, due to the heat effect of the reaction, it melts and a drop of metal, which is lighter than water, "runs" along the surface of the water, driven by the reactive force of the released hydrogen. Sodium interacts with alcohols much more calmly than with water:
Na + 2 C 2 H 5 OH = 2 C 2 H 5 ONa + H 2Sodium readily dissolves in liquid ammonia to form bright blue metastable solutions with unusual properties. At –33.8 ° C, up to 246 g of metallic sodium is dissolved in 1000 g of ammonia. Diluted solutions are blue, concentrated solutions are bronze. They can be stored for about a week. It was found that sodium ionizes in liquid ammonia:
Na Na + + e The equilibrium constant of this reaction is 9.9 · 10 –3. The outgoing electron is solvated by ammonia molecules and forms a complex [
e (NH 3) n ] -. The resulting solutions have metallic electrical conductivity. When ammonia evaporates, the original metal remains. With long-term storage of the solution, it gradually discolors due to the reaction of the metal with ammonia with the formation of amide NaNH 2 or imide Na 2 NH and the evolution of hydrogen.Sodium is stored under a layer of dehydrated liquid (kerosene, mineral oil), transported only in sealed metal vessels.
An electrolytic method for the industrial production of sodium was developed in 1890. The molten sodium hydroxide was subjected to electrolysis, as in Davy's experiments, but using more advanced energy sources than a volt pole. In this process, along with sodium, oxygen is released:
cathode (iron):
Na + + e - = Naanode (nickel): 4
OH - - 4 e - = O 2 + 2 H 2 O .In the electrolysis of pure sodium chloride, serious problems arise associated, firstly, with the close melting points of sodium chloride and the boiling point of sodium and, secondly, with the high solubility of sodium in liquid sodium chloride. The addition of potassium chloride, sodium fluoride, calcium chloride to sodium chloride makes it possible to reduce the melt temperature to 600 ° C. Sodium production by electrolysis of a molten eutectic mixture (an alloy of two substances with the lowest melting point) 40%
NaCl and 60% CaCl 2 at ~ 580 ° C in a cell developed by the American engineer H. Downes was launched in 1921 by DuPont near the power station near Niagara Falls.The following processes take place on the electrodes:
cathode (iron):
Na + + e - = Na Ca 2+ + 2 e - = Caanode (graphite): 2
Cl - - 2 e - = Cl 2 .Metallic sodium and calcium are formed on a cylindrical steel cathode and are lifted by a cooled tube in which the calcium solidifies and falls back into the melt. Chlorine generated at the central graphite anode is collected under the nickel dome and then purified.
Now the volume of sodium metal production is several thousand tons per year.
The industrial use of metallic sodium is due to its strong reducing properties. For a long time, most of the metal produced was used to obtain tetraethyl lead
PbEt 4 and tetramethyl lead PbMe 4 (antiknock agents for gasoline) by the reaction of alkyl chlorides with an alloy of sodium and lead at high pressure. Now this production is rapidly declining due to environmental pollution.Another area of application is the production of titanium, zirconium and other metals by reduction of their chlorides. Smaller amounts of sodium are used to make compounds such as hydride, peroxide, and alcoholates.
Dispersed sodium is a valuable catalyst in the production of rubber and elastomers.
The use of molten sodium as a heat exchange fluid in fast nuclear reactors is growing. The low melting point of sodium, low viscosity, small neutron absorption cross-section, combined with extremely high heat capacity and thermal conductivity, makes it (and its alloys with potassium) an irreplaceable material for these purposes.
Sodium reliably removes traces of water from transformer oils, ethers and other organic substances, and with the help of sodium amalgam, you can quickly determine the moisture content of many compounds.
Sodium compounds. Sodium forms a complete set of compounds with all common anions. It is believed that in such compounds there is an almost complete separation of the charge between the cationic and anionic parts of the crystal lattice.Sodium oxide
Na 2 O synthesized by reaction Na 2 O 2, NaOH , and most preferably NaNO 2, with sodium metal:Na 2 O 2 + 2Na = 2Na 2 O2NaOH + 2Na = 2Na 2 O + H 2
2 NaNO 2 + 6 Na = 4 Na 2 O + N 2In the latter reaction, sodium can be replaced with sodium azide
NaN 3: NaN 3 + NaNO 2 = 3 Na 2 O + 8 N 2Sodium oxide is best stored in anhydrous gasoline. It serves as a reagent for various syntheses.
Sodium peroxide
Na 2 O 2 in the form of a pale yellow powder is formed by the oxidation of sodium. In this case, under conditions of a limited supply of dry oxygen (air), an oxide is first formed Na 2 O which is then converted to peroxide Na 2 O 2. In the absence of oxygen, sodium peroxide is thermally stable up to ~ 675 ° C .Sodium peroxide is widely used in industry as a bleaching agent for fibers, paper pulp, wool, etc. It is a strong oxidizing agent: it explodes in a mixture with aluminum powder or charcoal, reacts with sulfur (while heating up), ignites many organic liquids. Sodium peroxide reacts with carbon monoxide to form carbonate. Oxygen is released in the reaction of sodium peroxide with carbon dioxide:
Na 2 O 2 + 2 CO 2 = 2 Na 2 CO 3 + O 2This reaction has important practical applications in breathing apparatus for divers and firefighters.
Sodium superoxide
NaO 2 is obtained by slowly heating sodium peroxide at 200–450 ° C under an oxygen pressure of 10–15 MPa. Evidence of education NaO 2 were first obtained in the reaction of oxygen with sodium dissolved in liquid ammonia.The action of water on sodium superoxide leads to the release of oxygen even in the cold:
NaO 2 + H 2 O = NaOH + NaHO 2 + O 2As the temperature rises, the amount of oxygen released increases, as the resulting sodium hydroperoxide decomposes:
NaO 2 + 2 H 2 O = 4 NaOH + 3 O 2Sodium superoxide is a component of indoor air regeneration systems.
Sodium ozonide
Na О 3 is formed by the action of ozone on anhydrous sodium hydroxide powder at a low temperature, followed by the extraction of red Na About 3 liquid ammonia.Sodium hydroxide
NaOH often called caustic soda or caustic soda. It is a strong base and is classified as a typical alkali. Numerous hydrates have been obtained from aqueous solutions of sodium hydroxide NaOH nH 2 O, where n = 1, 2, 2.5, 3.5, 4, 5.25 and 7.Sodium hydroxide is highly corrosive. It destroys glass and porcelain by interacting with the silicon dioxide they contain:
NaOH + SiO 2 = Na 2 SiO 3 + H 2 OThe name "caustic soda" reflects the corrosive effect of sodium hydroxide on living tissue. It is especially dangerous to get this substance in the eyes.
Physician to the Duke of Orleans Nicolas LeBlanc (
Leblanc Nicolas ) (1742-1806) in 1787 developed a convenient process for obtaining sodium hydroxide from NaCl (patent 1791). This first large-scale industrial chemical process was a major technological breakthrough in Europe in the 19th century. Later, the Leblanc process was superseded by the electrolytic process. In 1874 the world production of sodium hydroxide was 525 thousand tons, of which 495 thousand tons were obtained by the Leblanc method; by 1902, the production of sodium hydroxide had reached 1800 thousand tons, but only 150 thousand tons were obtained by the Leblanc method.Sodium hydroxide is the most important alkali in the industry today. Annual production in the USA alone exceeds 10 million tons. It is obtained in huge quantities by electrolysis of brines. During the electrolysis of a sodium chloride solution, sodium hydroxide is formed and chlorine is released:
cathode (iron) 2
H 2 O + 2 e - = H 2 + 2 OH anode (graphite) 2
Cl - - 2 e - = Cl 2Electrolysis is accompanied by the concentration of alkali in huge evaporators. The largest in the world (at the factory
PPG Inductries "Lake Charles ) has a height of 41 m and a diameter of 12 m.About half of the sodium hydroxide produced is used directly in the chemical industry to obtain various organic and inorganic substances: phenol, resorcinol, b -naphthol, sodium salts (hypochlorite, phosphate, sulfide, aluminates). In addition, sodium hydroxide is used in the production of paper and pulp, soaps and detergents, oils, textiles. It is also required in the processing of bauxite. An important area of application of sodium hydroxide is in the neutralization of acids.Sodium chloride
NaCl known under the names of table salt, rock salt. It forms colorless, slightly hygroscopic, cubic crystals. Sodium chloride melts at 801 ° C, boils at 1413 ° C. Its solubility in water depends little on temperature: 35.87 g dissolves in 100 g of water at 20 ° C NaCl , and at 80 ° C - 38.12 g.Sodium chloride is a necessary and irreplaceable food seasoning. In the distant past, salt was equated in price with gold. In ancient Rome, legionnaires were often paid salaries not in money, but in salt, hence the word soldier.
In Kievan Rus, they used salt from the Carpathian region, from salt lakes and estuaries on the Black and Azov seas. It was so expensive that at solemn feasts it was served on the tables of noble guests, while the others dispersed "unhappily".
After the annexation of the Astrakhan Territory to the Moscow State, the Caspian lakes became important sources of salt, and still it was not enough, it was expensive, therefore there was discontent among the poorest segments of the population, which grew into an uprising known as the Salt Riot (1648)
In 1711, Peter I issued a decree on the introduction of the salt monopoly. Salt trade has become the exclusive right of the state. The salt monopoly existed for over 150 years and was abolished in 1862.
Today sodium chloride is a cheap product. Together with coal, limestone and sulfur, it is included in the so-called "big four" mineral raw materials, the most essential for the chemical industry.
Most of sodium chloride is produced in Europe (39%), North America (34%) and Asia (20%), while South America and Oceania only account for 3% and Africa 1%. Rock salt forms vast underground deposits (often hundreds of meters thick), which contain more than 90%
NaCl ... The typical Cheshire salt deposit (the main source of sodium chloride in the UK) covers an area of 60ґ 24 km and has a salt layer thickness of about 400 m. This field alone is estimated at more than 10 11 tons.The world volume of salt production by the beginning of the 21st century. reached 200 million tons, 60% of which is consumed by the chemical industry (for the production of chlorine and sodium hydroxide, as well as paper pulp, textiles, metals, rubbers and oils), 30% - food, 10% falls on other areas of activity. Sodium chloride is used, for example, as a cheap deicing agent.
Sodium carbonate
Na 2 CO 3 is often called soda ash or just soda ash. It occurs naturally in the form of ground brines, brines in lakes and natron minerals. Na 2 CO 3 10 H 2 O, thermosatrite Na 2 CO 3 H 2 O, thrones Na 2 CO 3 NaHCO 3 2 H 2 O ... Sodium forms a variety of other hydrated carbonates, bicarbonates, mixed and double carbonates, for example Na 2 CO 3 7 H 2 O, Na 2 CO 3 3 NaHCO 3, aKCO 3 nH 2 O, K 2 CO 3 NaHCO 3 2 H 2 O .Among the salts of alkaline elements obtained in industry, sodium carbonate is of the greatest importance. Most often, for its production, the method developed by the Belgian chemist-technologist Ernst Solve in 1863 is used.
A concentrated aqueous solution of sodium chloride and ammonia is saturated with carbon dioxide under low pressure. In this case, a precipitate of relatively poorly soluble sodium bicarbonate is formed (solubility
NaHCO 3 is 9.6 g per 100 g of water at 20 ° C):NaCl + NH 3 + H 2 O + CO 2 = NaHCO 3Ї + NH 4 Cl To obtain soda, sodium bicarbonate is calcined: NaHCO 3 = Na 2 CO 3 + CO 2 + H 2 OThe emitted carbon dioxide is returned to the first process. An additional amount of carbon dioxide is obtained by calcining calcium carbonate (limestone):
CaCO 3 = CaO + CO 2The second product of this reaction, calcium oxide (lime), is used to regenerate ammonia from ammonium chloride:
CaO + 2 NH 4 Cl = CaCl 2 + 2 NH 3 + H 2 OThus, the only by-product of Solvay soda production is calcium chloride.
The overall equation of the process:
NaCl + CaCO 3 = Na 2 CO 3 + CaCl 2Obviously, under normal conditions, the reverse reaction takes place in an aqueous solution, since the equilibrium in this system is completely shifted from right to left due to the insolubility of calcium carbonate.
Soda ash obtained from natural raw materials (natural soda ash) has a better quality compared to soda ash obtained by the ammonia method (chloride content less than 0.2%). In addition, the specific capital investments and the cost of soda from natural raw materials are 40–45% lower than those obtained synthetically. About a third of the world's soda production is now accounted for by natural deposits.
World production
Na 2 CO 3 in 1999 was distributed as follows:| Total | |
| North. America | |
| Asia / Oceania | |
| Zap. Europe | |
| East Europe | |
| Africa | |
| Lat. America |
Unlike the United States, most countries in the world are almost entirely dependent on the production of synthetic soda ash. China is the second largest producer of soda ash after the United States. The production of this chemical in the PRC in 1999 reached about 7.2 million tons. The production of soda ash in Russia in the same year was about 1.9 million tons.
In many cases, sodium carbonate is interchangeable with sodium hydroxide (for example, when making paper pulp, soap, cleaning agents). About half of sodium carbonate is used in the glass industry. One of the growing areas of application is the removal of sulphurous contaminants in gas emissions from power plants and powerful furnaces. Sodium carbonate powder is added to the fuel, which reacts with sulfur dioxide to form solid products, in particular sodium sulfite, which can be filtered off or precipitated.
Previously, sodium carbonate was widely used as a "washing soda", but this area of application has now disappeared due to the use of other detergents in the home.
Sodium bicarbonate
NaHCO 3 (baking soda), is mainly used as a source of carbon dioxide in baking bread, making confectionery, producing carbonated drinks and artificial mineral waters, as a component of fire extinguishing compositions and as a medicine. This is due to the ease of its decomposition at 50-100° WITH.Sodium sulfate
Na 2 SO 4 occurs in nature in anhydrous form (thenardite) and in the form of decahydrate (mirabilite, Glauber's salt). It is part of astrakhonite Na 2 Mg (SO 4) 2 4 H 2 O, vanthoffite Na 2 Mg (SO 4) 2, glauberite Na 2 Ca (SO 4) 2. The largest reserves of sodium sulfate are in the CIS countries, as well as in the USA, Chile, Spain. Mirabilite, isolated from natural deposits or brine from salt lakes, is dehydrated at 100 ° C. Sodium sulfate is also a by-product of the production of hydrogen chloride using sulfuric acid, as well as the end product of hundreds of industrial industries that use neutralization of sulfuric acid with sodium hydroxide.Data on the production of sodium sulfate are not published, but it is estimated that the world production of natural raw materials is about 4 million tons per year. The extraction of sodium sulfate as a by-product is estimated in the world as a whole at 1.5–2.0 million tons.
For a long time, sodium sulfate was little used. Now this substance is the basis of the paper industry, since
Na 2 SO 4 is the main reagent in kraft pulping for preparing brown wrapping paper and corrugated board. Wood shavings or sawdust are processed in a hot alkaline sodium sulfate solution. It dissolves lignin (the fiber-binding component in wood) and releases cellulose fibers, which are then sent to papermaking machines. The remaining solution is evaporated until it has the ability to burn, providing steam for the plant and heat for evaporation. Molten sodium sulfate and sodium hydroxide are flame resistant and can be reused.A smaller proportion of sodium sulfate is used in the manufacture of glass and detergents. Hydrated form
Na 2 SO 4 10 H 2 O (Glauber's salt) is a laxative. It is used less now than it used to be.Sodium nitrate
NaNO 3 is called sodium or Chilean nitrate. The large deposits of sodium nitrate found in Chile appear to have formed from the biochemical decomposition of organic debris. The ammonia released at the beginning was probably oxidized to nitrous and nitric acids, which then reacted with dissolved sodium chloride.Sodium nitrate is obtained by absorption of nitrous gases (mixture of nitrogen oxides) with a solution of sodium carbonate or hydroxide, or by exchange interaction of calcium nitrate with sodium sulfate.
Sodium nitrate is used as a fertilizer. It is a component of liquid salt refrigerants, quenching baths in the metalworking industry, heat storage compounds. Triple blend of 40%
NaNO 2, 7% NaNO 3 and 53% KNO 3 can be used from the melting point (142 ° C) to ~ 600 ° C. Sodium nitrate is used as an oxidizing agent in explosives, rocket fuels, and pyrotechnic compositions. It is used in the production of glass and sodium salts, including nitrite, a food preservative.Sodium nitrite
NaNO 2 can be obtained by thermal decomposition of sodium nitrate or its reduction: NaNO 3 + Pb = NaNO 2 + PbOFor industrial production of sodium nitrite, nitrogen oxides are absorbed with an aqueous solution of sodium carbonate.
Sodium nitrite
NaNO 2, in addition to being used with nitrates as heat-conducting melts, is widely used in the production of azo dyes, to inhibit corrosion and preserve meat.Helena
Savinkina LITERATURE Popular library of chemical elements. M., Science, 1977Greenwood N.N., Earnshaw A. Chemistry of the Elements, Oxford: Butterworth, 1997
Water is a unique substance with a complex molecular structure that has not yet been fully studied. Regardless of the state of aggregation, H2O molecules are tightly bound to each other, which determines many physical properties of water and its solutions. Let's find out if ordinary water has thermal and electrical conductivity.
The main physical properties of H2O are:
- density;
- transparency;
- Colour;
- smell;
- taste;
- temperature;
- compressibility;
- radioactivity;
- heat and electrical conductivity.
The latter characteristics of thermal conductivity and electrical conductivity of water are very unstable and depend on many factors. Let's consider them in more detail.
Electrical conductivity
Electric current is a one-way movement of negatively charged particles - electrons. Some substances can carry these particles, and some cannot. This ability is expressed in numerical form and represents the value of electrical conductivity.
There is still debate about whether pure water is electrically conductive; it can conduct current, but very poorly. The electrical conductivity of the distillate is explained by the fact that H2 O molecules partially decompose into H + and OH- ions. Electroparticles are propelled by positively charged hydrogen ions, which are able to move through the water column.
What determines the electrical conductivity of a liquid
The conductivity of H2 O depends on factors such as:
- presence and concentration of ionic impurities (mineralization);
- the nature of the ions;
- fluid temperature;
- viscosity of water.
The first two factors are decisive. Therefore, by calculating the value of the electrical conductivity of the liquid, we can judge the degree of its mineralization.
Pure water does not exist in nature. Even spring water is a kind of solution of salts, metals and other electrolyte impurities. These are primarily ions Na +, K +, Ca2 +, Cl-, SO4 2-, HCO3 -. Also, it may contain weak electrolytes, which are unable to greatly change the property of conducting current. These include Fe3 +, Fe2 +, Mn2 +, Al3 +, NO3 -, HPO4 - and others. They can have a strong effect on electrical conductivity only in the case of a high concentration, as, for example, it happens in waste water with industrial waste. Interestingly, the presence of impurities in water, which is in the ice state, does not affect its ability to conduct electricity.
Electrical conductivity of sea water
Sea water is better able to conduct electricity than fresh water. This is due to the presence of a dissolved NaCl salt in it, which is a good electrolyte. The mechanism for increasing conductivity can be described as follows:
- Sodium chloride, when dissolved in water, decomposes into Na + and Cl- ions, which have different charges.
- Na + ions attract electrons because they have opposite charges.
- The movement of sodium ions in the water column leads to the movement of electrons, which, in turn, leads to the emergence of an electric current.
Thus, the electrical conductivity of water is determined by the presence of salts and other impurities in it. The fewer there are, the lower the ability to conduct electric current. For distilled water, it is practically zero.
Measurement of electrical conductivity
Measurement of the electrical conductivity of solutions is carried out using conductometers. These are special devices, the principle of which is based on the analysis of the ratio of electrical conductivity and concentration of impurities-electrolytes. Today, there are many models that are able to measure the conductivity of not only highly concentrated solutions, but also pure distilled water.
Thermal conductivity
Thermal conductivity is the ability of a physical substance to conduct heat from heated parts to colder ones. Water, like other substances, has this property. Heat transfer occurs either from molecule to molecule H2 O, which is a molecular type of thermal conductivity, or when fluid flows move - a turbulent type.
The thermal conductivity of water is several times higher than that of other liquid substances, with the exception of molten metals - they have this indicator even higher.
The ability of water to conduct heat depends on two factors: pressure and temperature. With an increase in pressure, the conductivity index increases, with an increase in temperature to 150 ° C, it increases, then begins to decrease.
Why does the pool water seem cold to us?
The thermal conductivity of water is several tens of times higher than that of air. When a person is immersed in water or simply doused with it, heat loss increases, so it becomes much colder than in air of the same temperature. This can be seen in the examples given in the table:
The most interesting facts about water: Video
Rozanov Evgeniy
Soda is a multifaceted substance, its use is different. Soda is used from the food industry to metallurgy. I became interested in these substances that everyone has in the house and decided to study how the various properties of an aqueous solution of soda manifest themselves depending on the temperature and concentration of the solution.
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Completed by: Evgeniy Rozanov. Academic Supervisor: Khabarova Olga Nikolaevna
Doroninskoe soda lake is a hydrological natural monument, the largest soda lake in Eastern Siberia. The area of the reservoir in different seasons and years varies from 3.7 to 4.8 km2. The average depth of the water is about 4 m, the greatest is 6.5 m. On the lake there is the most famous deposit of self-precipitated soda in Transbaikalia.
Dioscorides Pedanius Greek by origin, physician, pharmacologist and naturalist, one of the founders of botany, Dioscorides Pedanius was born in Anazarba, Cilicia, Asia Minor (modern Nazarva). Dioscorides traveled a lot with the Roman army under the emperor Nero, practicing military medicine, collecting and identifying plants. The main work of Dioscorides - "De materia medica" ("On medicinal substances") contains a description of 600 plants, 1000 different medicinal preparations. In the Middle Ages, "De materia medica" was considered the main source of knowledge in botany and pharmacology.
Henri Louis Duhamel du Monceau Peter the Great
LeBlanc He studied medicine, attended lectures on chemistry by G. Ruel in the Botanical Garden of Paris. In 1791, Nicola Leblanc received a patent for "A Method for Converting Glauber's Salt to Soda". LeBlanc offered his technology for producing soda to the Duke Philip of Orleans, whose personal physician he was. In 1789, the Duke signed an agreement with LeBlanc and allocated him two hundred thousand silver livres for the construction of the plant. A soda plant in the suburbs of Paris Saint-Genis was called "Franciade - Leblanc Soda" and daily produced 100-120 kg of soda. During the French Revolution in 1793, the Duke of Orleans was executed, his property confiscated, and the soda factory and the Leblanc patent itself were nationalized. Only seven years later, LeBlanc was returned to the ruined plant, which he had not been able to restore.
Purpose: To investigate the dependence of the electrical conductivity of an aqueous solution of baking soda on the temperature and concentration of the aqueous solution.
Objectives: To study the literature on the research topic. Conduct a knowledge survey on the various uses of baking soda. Learn to prepare a solution of baking soda of various concentrations. Investigate the dependence of electrical conductivity on the concentration of the solution and temperature.
Relevance of research Soda is a multifaceted substance, its application is different. Soda is used from the food industry to metallurgy. Knowing its properties is always relevant.
Soda is a multifaceted substance
Scope of application of baking soda chemical light industry textile industry food industry medical industry metallurgy
Chemical industry In the chemical industry - for the production of dyes, foams and other organic products, fluoride reagents, household chemicals.
Metallurgy In metallurgy - in the precipitation of rare earth metals and ore flotation.
Textile and light textile industry (finishing of silk and cotton fabrics). light industry - in the production of sole rubber and artificial leather, tanning (tanning and neutralization of leather).
Food industry In the food industry - bakery, confectionery, beverage preparation.
Medical industry In the medical industry - for the preparation of injection solutions, anti-tuberculosis drugs and antibiotics
Questionnaire In what areas of industry do you think baking soda is used: Food industry Medicine Metallurgy Chemical industry Light industry At home
Poll results
Conclusion from the survey Most of the respondents answered that soda is used most often in everyday life, in the food industry, in the chemical industry.
Hypothesis If you increase the concentration of an aqueous solution of baking soda, then its electrical conductivity will increase.
Experience No. 1 "Preparation of an aqueous solution of baking soda" Purpose: to learn how to prepare an aqueous solution of baking soda of various concentrations. Equipment: 3 beakers, baking soda, filtered water, scales, weights.
No. Mass of soda (g) Mass of water (ml) Concentration of soda (%) 1 4 96 4 2 8 92 8 3 12 88 12
Conclusion: Experimentally I learned to prepare an aqueous solution of baking soda of various concentrations.
Experiment No. 2 "Investigation of the electrical conductivity of a baking soda solution" Purpose: to prove that with an increase in the concentration of a baking soda solution, its electrical conductivity increases. Equipment: Power supply, 2 electrodes, 3 glasses with soda solution of various concentrations, ammeter, voltmeter, connecting wires, key
Installation diagram
Table No. Soda ash concentration I (A) U (B) R (Ohm) λ = 1 / R (1 / Ohm = Cm) 1 4 1.0 6 6 0.17 2 8 1.4 6 4.9 0.23 3 12 1.7 6 3.53 0.28
Formulas for calculating R = U / I (Ohm = V / A) λ = 1 / R (1 / Ohm = Cm) (Siemens)
Conclusion: Experimentally I learned to determine the electrical conductivity of baking soda and was convinced that the higher the concentration of the solution, the greater the electrical conductivity of the baking soda solution. And the resistance of the solution, with increasing concentration, decreases.
Experiment No. 3 "Investigation of the dependence of electrical conductivity on the temperature of the solution" Purpose: Make sure that the electrical conductivity of the solution depends on the temperature. Equipment: Thermometer, Power supply, 2 electrodes, 3 glasses with soda solution of various concentrations, ammeter, voltmeter, connecting wires, key, heating element.
Table of% solution t о С solution I (A) U (B) R (Ohm) λ (Cm) 4 18 1 6 6 0.17 19 1.03 6 5.83 0.172 20 1.05 6 5.71 0.175 21 1.08 6 5.56 0.180 22 1.1 6 5.45 0.183
Graph 1. Dependence of solution resistance on temperature
Graph 2. Dependence of electrical conductivity on temperature
Conclusion: It is obvious from experience that electrical conductivity increases with increasing temperature. When heated, the speed of ions increases, thereby accelerating the transfer of charges from one point to another, from one electrode to another.
Conclusion: After studying the literature on the research topic, conducting a sociological survey, we came to the conclusion: Soda is a multifaceted substance with different properties. The resistance of a soda solution depends on its concentration. The conductivity of a solution is also concentration dependent. The electrical conductivity increases with increasing temperature.
Thank you for the attention!
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Research
"Study of the electrical conductivity of an aqueous solution of baking soda"
Introduction
Soda was known to man for about one and a half to two thousand years BC, and maybe even earlier. It was mined from soda lakes and extracted from a few deposits in the form of minerals. The first information about obtaining soda by evaporating water from soda lakes dates back to 64 AD. Alchemists of all countries, up to the 18th century, seemed to be a kind of substance that sizzled with the release of some kind of gas under the action of acids known by that time - acetic and sulfuric. At the time of the Roman physician Dioscorides Pedania, no one had a clue about the composition of soda. In 1736, the French chemist, physician and botanist Henri Louis Duhamel de Monceau was able to obtain very pure soda from the water of soda lakes for the first time. He was able to establish that the soda contains the chemical element "Natr". In Russia, even at the time of Peter the Great, soda was called "zoda" or "itch" and until 1860 it was imported from abroad. In 1864, the first soda plant based on the technology of the Frenchman Leblanc appeared in Russia. It was thanks to the appearance of its own factories that soda became more accessible and began its victorious path as a chemical, culinary and even medicine.
In industry, trade and in everyday life, several products are found under the name of soda: soda ash - anhydrous sodium carbonate Na 2 CO 3 , bicarbonate soda - sodium bicarbonate NaHCO 3
, often called baking soda, crystalline soda Na 2 CO 3 10H 2 O and Na 2 CO 3 H 2 O and caustic soda, or caustic soda, NaOH.
Modern baking soda is a typical industrial product
Currently, the world produces several million tons of soda per year for various uses.
Soda is a multifaceted substance, its use is different. Soda is used from the food industry to metallurgy. I became interested in these substances that everyone has in the house and decided to study how the various properties of an aqueous solution of soda manifest themselves depending on the temperature and concentration of the solution.
So, we had a goal:
To investigate the dependence of the electrical conductivity of an aqueous solution of baking soda on the temperature and concentration of the aqueous solution.
Tasks:
- Examine the literature on the research topic.
- Conduct a knowledge survey on the various uses of baking soda.
- Learn to prepare a solution of baking soda of various concentrations.
- Investigate the dependence of electrical conductivity on the concentration of the solution and temperature.
The relevance of research:
Soda is a multifaceted substance, its use is different. Soda is used from the food industry to metallurgy. Knowing its properties is always relevant.
The slide shows the main uses of baking soda.
- chemical industry
- light industry
- textile industry
- food industry
- medical industry
- metallurgy
So, in the chemical industry - for the production of dyes, foams and other organic products, fluoride reagents, household chemicals.
- In metallurgy - during the precipitation of rare earth metals and ore flotation.
- In the textile industry (finishing silk and cotton fabrics).
- In the light industry - in the production of sole rubber and artificial leather, tanning (tanning and neutralization of leather).
- In the food industry - bakery, confectionery, beverage preparation.
- In the medical industry - for the preparation of injection solutions, anti-tuberculosis drugs and antibiotics
After studying theoretical material, I decided to ask my classmates if they know in what areas of industrybaking soda is used:
- At home
- Food industry
- Medicine
- Chemical industry
- Metallurgy
- Light industry
Here are the results of the survey: the largest number of respondents answered:
- At home -63%
- Food industry-71%
- Chemical industry - 57%, the smallest number of respondents indicated the use of soda in metallurgy and light industry.
For further research, it was necessary for me to prepare an aqueous solution of various concentrations.
Hypothesis
So, if you increase the concentration of an aqueous solution of baking soda, then its electrical conductivity will increase.
II. experimental part
"Study of the electrical conductivity of an aqueous solution of baking soda"
Target: make sure that there are carriers of electricity in an aqueous solution of soda - ions that conduct an electric current.
Equipment: baking soda, chemical glasses made of heat-resistant glass, electrodes, connecting wires, power supply, ammeter, voltmeter, key, laboratory scales, weights, thermometer, electric stove.
Experience 1. "Preparation of an aqueous solution of baking soda"
Target: Learn to prepare an aqueous solution of baking soda of various concentrations.
Equipment: chemical glasses made of heat-resistant glass, filtered water, scales, weights, baking soda.
Experience execution:
- Hang 4 g of baking soda on the scales;
- Pour 96 ml into a beaker. filtered water;
- Pour soda into a glass of water and mix thoroughly;
- Repeat the experiment to prepare a solution of 8% and 12%
Soda weight (g) | Amount of water (ml) | soda concentration in (%) |
|
Output: Experimentally, I learned how to prepare an aqueous solution of baking soda of various concentrations.
Experience 2. "Study of the electrical conductivity of a baking soda solution"
Target: prove that with an increase in the concentration of soda solution, its electrical conductivity increases.
Equipment: three glasses with a solution of baking soda of various concentrations, a power source, an ammeter, a voltmeter, connecting wires, a wrench, electrodes.
Resistivity is a scalar value numerically equal to the resistance of a homogeneous cylindrical conductor of unit length and unit area... The greater the specific resistance of the conductor material, the greater its electrical resistance.
The unit of resistivity is ohm meter (1 ohm m).
Experience execution:
- Assemble the electrical circuit according to the diagram;
- Place the electrodes in a beaker with a concentration of 4%, 8% and 12% baking soda solution;
- Measure the readings of the ammeter and voltmeter;
- Calculate the resistance of the solution;
- Calculate the conductivity of the solution.
Table 2.
Soda concentration | I (A) | U (B) | R (Ohm) | λ = 1 R (1Ω = cm) |
|
0,17 |
|||||
0,23 |
|||||
3,53 | 0,28 |
For the experiment, an electrical circuit was assembled according to the scheme. By changing the concentration of the aqueous solution, we record the readings of the ammeter and voltmeter.
The measurements were carried out at a temperature of 18 0 C and atmospheric pressure 757 mm Hg.
Output: Experimentally, I learned to determine the electrical conductivity of baking soda and was convinced that the higher the concentration of the solution, the greater the electrical conductivity of the baking soda solution. And the resistance of the solution, with increasing concentration, decreases. Consequently, with a 12% baking soda solution, conductivity will be highest and resistance lowest.
Experience 3. "Study of the dependence of electrical conductivity on the temperature of the solution"
Target: Check that conductivity changes with temperature.
Equipment: three glasses with a solution of baking soda of various concentrations, a power source, an ammeter, a voltmeter, connecting wires, a wrench, electrodes, a thermometer, an electric stove.
Experience execution:
- Assemble the installation according to the scheme;
- Put a 4% baking soda solution on the tile;
- Turn on tiles;
- Record the temperature of the solution;
- Measure the readings of the ammeter and voltmeter through each degree of the solution;
- Calculate resistance and electrical conductivity using the formulas.
1,05
5,71
0,175
1,08
5,56
0,180
5,45
0,183
λ = 1R (1Ω = cm)
Output: It is obvious from experience that electrical conductivity increases with temperature. When heated, the speed of ions increases, thereby accelerating the transfer of charges from one point to another.
Graph 1. The dependence of the resistance of the solution on temperature.
Graph 2. Dependence of electrical conductivity on temperature
Conclusion
Having studied the literature on the properties of baking soda, its use in medicine, food industry, everyday life, after doing a number of experiments, we were convinced that:
- Soda is a multifaceted substance with different properties
- The resistance of the soda solution depends on its concentration.
- The conductivity of a solution is also concentration dependent.
- The electrical conductivity increases with increasing temperature.
Literature
- General chemical technology. Ed. I.P. Mukhlenova. Textbook for chemical-technological specialties of universities. - M .: Higher school.
- Fundamentals of General Chemistry, vol. 3, B.V. Nekrasov. - M .: Chemistry, 1970.
- General chemical technology. Furmer I.E., Zaitsev V.N. - M .: Higher school, 1978.
- General Chemical Technology, ed. I. Volfkovich, vol. 1, Soda M. - L., 1953, p. 512-54;
- Benkovsky V., Technology of sodoproducts, M, 1972;
- Shokin I. N., Krasheninnikov Soda A., Soda Technology, M., 1975.
