Sodium sulfate aqueous solution. Sodium sulfate (sodium sulfate)
The use of sodium sulfate (Na2SO4) is associated with the manufacture of shampoos, powders, laxatives medical preparations, food. Chemical element used by the chemical, textile, leather industries. It has both a number of advantages and disadvantages, among which is the fragility of the hair when washing with shampoos, where ingredients of the derivative type lauryl and laureth sulfates are present.
What is sodium sulfate
Sodium sulfate is a substance that has the name analogous to sodium sulfate and defines a whole class of sulfuric acid salts from the sodium category. Glauber's salt is the decahydrate of the above substance, previously used to cleanse the intestines after poisoning as a laxative. In modern America and Russia, for this purpose, sodium sulfate, together with its hydrates, is not allowed to be used as a single active substance.
Formula
The formula of sodium sulfate in its anhydrous version is designated as Na2SO4 with a molar mass of 142 g / mol, has no color, has a crystalline form. IN natural conditions anhydrous sodium sulfate is found as the mineral thenardite. Up to a temperature of thirty-four degrees, the element is stable. If you increase the temperature and add water, the substance is converted into Glauber's salt (the name of the mineral is mirabilite).
Properties
The properties of sodium sulfate are as follows:
- the shape of the crystals is diamond-shaped;
- no color;
- boiling and melting occurs without decomposition;
- dissolution in water is fast;
- the reaction with hydrogen starts at a temperature range from 550 to 600 degrees;
- reacts with sulfuric acid.
The use of sodium sulfate in industry
The use of sodium sulfate in industry has many branches, ranging from the production of washing powders, ending with the use as food additive. Areas of use:
- Food industry. Sodium sulphate solution is added to products under the code E514 to regulate acidity, whitening, increase the shelf life of food, color stabilizer. Manufacturers send it to dried fish products, canned fruits, vegetables, jelly, marmalade, confectionery, seasonings. On molecular level the substance binds acetaldehyde in wine, preventing the drink from oxidizing. For health, the additive is harmful, like all substances with the presence of E, it has destructive action for vitamins E, B1.
- Chemical and cosmetic industry. For the manufacture of detergents: shampoo, powder, shower gel, floor cleaner.
- Medicine. It is found in drugs that have a laxative effect, slows down the absorption of poison in the intestines.
- May be found as a dehydrator in science labs to replace magnesium sulfate, as it is cheaper and takes less time to produce.
- Other areas of application are glass production, non-ferrous metallurgy, leather and textile industries.
Sodium sulfate in shampoos
On the label, it is designated SLS (sodium laureth sulfate) - this is sodium laureth sulfate, originally invented for washing tanks during World War II, but due to its excellent laundering qualities and beautiful foam, the substance passed into the cosmetic industry. Sodium sulfate is very common in shampoos. Lauryl sulfate is considered even more concentrated and harmful.
Although the American College of Toxicology has debunked the cancer-causing association of laureth and lauryl sulfates, these compounds have some negative effects on skin and hair. If you use shampoos with these additives too often, you can get dry, dull hair, inflammation of the scalp. natural substitutes: lauryl glucoside, laureth sulfosuccinate, cocoglucoside may foam less, but are more beneficial for washing.
Sodium sulfate
The element promotes the excretion of bile, prevents the absorption of toxic substances. Sodium sulfate retains fluid in the intestines, and its accumulation stimulates peristalsis and emptying gastrointestinal tract. This effect of the substance is used for the production of saline laxatives. Has the form of a powder to be drunk as water solution. Begins to act 5 hours after ingestion.
Instructions for use
Indications:
- preparatory stage before surgical intervention into the intestines;
- prolonged constipation;
- food poisoning;
- together with other preparations for cleansing helminths.
Instructions for the use of sodium sulfate:
Before use, the powder is poured boiled warm water(a quarter of a glass) at the rate of 1 gram per year of life for a child and from 15 to 30 grams for an adult. Drink on an empty stomach. Not to be used by pregnant women, people with inflammatory diseases Gastrointestinal tract, during breastfeeding, menstruation, with hemorrhoids. It is worth refraining from using it for the elderly and people with severe exhaustion organism. Before use, you should get the approval of the doctor and carefully read the instructions.
Video
DEFINITION
Sodium sulfate is a substance white color(Fig. 1), the crystals of which melt without decomposition. It dissolves well in water (does not hydrolyze).
It crystallizes from aqueous solutions with ten water molecules (Na 2 SO 4 × 10H 2 O) and in this form is called Glauber's salt after the German physician and chemist I.R. Glauber, who was the first to obtain it by the action of sulfuric acid on sodium chloride.
Rice. 1. Sodium sulfate. Appearance.
Table 1. Physical Properties sodium sulfate.
Obtaining sodium sulfate
Basic industrial way obtaining sodium sulfate is not much different from what was used by I.R. Glauber when he first received this salt. The exchange reaction between sulfuric acid and sodium chloride, carried out when heated to 500 o C in a special furnace:
2NaCl + H 2 SO 4 = Na 2 SO 4 + 2HCl.
In addition, sodium sulfate occurs in nature as the mineral thenardite (anhydrous) and mirabilite (hydrate).
Chemical properties of sodium sulfate
In an aqueous solution, sodium sulfate dissociates into ions:
Na 2 SO 4 ↔ 2Na + + SO 4 2-.
Solid sodium sulfate reacts with concentrated sulfuric acid
Na 2 SO 4 + H 2 SO 4 (conc) = 2NaHSO 4 (solution) .
Enters into exchange reactions with acid oxides (1), hydroxides (2) and salts (3):
Na 2 SO 4 + SO 3 \u003d Na 2 S 2 O 7 (1);
Na 2 SO 4 + Ba(OH) 2 = BaSO 4 ↓ + 2NaOH (2);
Na 2 SO 4 + BaCl 2 = BaSO 4 ↓ + 2NaCl (3).
Sodium sulfate is reduced by hydrogen (4) and carbon (5):
Na 2 SO 4 + 4H 2 \u003d Na 2 S + 4H 2 O (t \u003d 550 - 600 o C6 kat \u003d Fe 2 O 3) (4);
Na 2 SO 4 + 2C + CaCO 3 \u003d Na 2 CO 3 + CaS + CO 2 (t \u003d 1000 o C) (5).
Application of sodium sulfate
Anhydrous sodium sulfate is used to make glass. Previously, this salt was used as one of the constituents of washing powders and other detergents. In addition, sodium sulfate has found application in the textile industry, leather business, production of non-ferrous metals, as well as in chemical analysis.
Examples of problem solving
EXAMPLE 1
EXAMPLE 2
| Exercise | Calculate the amount of heat released during the formation of sodium sulfate from sodium peroxide weighing 7.5 g and sulfur oxide (IV). The thermochemical reaction equation has the following form: |
| Solution | Let us write again the thermochemical reaction equation: Na 2 O 2 + SO 2 = Na 2 SO 4 + 654.4 kJ. According to the reaction equation, 1 mol of sodium peroxide and 1 mol of sulfur oxide (IV) entered into it. Calculate the mass of sodium peroxide according to the equation, i.e. theoretical mass (molar mass- 78 g/mol): m theor (Na 2 O 2) \u003d n (Na 2 O 2) × M (Na 2 O 2); m theor (Na 2 O 2) \u003d 1 × 78 \u003d 78 g. Let's make a proportion: m prac (Na 2 O 2) / m theor (Na 2 O 2) \u003d Q prac / Q theor. Then, the amount of heat released during the reaction of interaction between sodium peroxide and sulfur oxide (IV) is equal to: Q prac \u003d Q theor × m prac (Na 2 O 2) / m theor (Na 2 O 2); Q prac \u003d 654.4 × 7.5 / 78 \u003d 62.92 kJ. |
| Answer | The amount of heat is 62.92 kJ. |
Sodium sulfate (Sodium sulfate) – sodium salt sulfuric acid.
Physicochemical characteristics.
The chemical formula of Na 2 SO 4 is sodium sulfate (anhydrous sodium sulfate, anhydrous sodium sulfate, thenardite). Colorless rhombic crystals. Density 2.7 g/cm 3 . Melting point 884°C. Anhydrous sodium sulfate is stable above a temperature of 32.384 ° C, below this temperature, in the presence of water, Na 2 SO 4 10H 2 O crystalline hydrate (sodium sulfate decahydrate) is formed.
Formula Na 2 SO 4 × 10H 2 O - sodium sulfate decahydrate (sodium sulfate decahydrate, Glauber's salt, mirabilite). Large colorless prismatic crystals of the monoclinic system, bitter-salty taste. Density 1.46 g/cm 3 . Melting point 32.384 °C. Decomposition temperature 32.384 °C. In air, it decomposes into anhydrous sodium sulfate and water. Normally soluble in ethanol. Let's well dissolve in water.
Application.
Sodium sulfate is used as one of the main components of the charge in glass production; in the processing of wood (sulphite pulping), in the dyeing of cotton fabrics, for the production of viscose silk, various chemical compounds- sodium silicate and sulfide, ammonium sulfate, soda, sulfuric acid. Sodium sulfate is used in construction as an antifreeze additive and an accelerator for setting the concrete mix. Sodium sulfate is also used in the production of synthetic detergents; sodium sulfate solutions are used as a heat accumulator in devices that store solar energy.
The use of sodium sulfate in glass production.
Sodium sulfate is used mainly as a clarifying additive in an amount of 3 to 10%, depending on the amount of soda. It is introduced into the composition of raw materials not only as a source of Na 2 O , but also SO 3 , which is necessary to increase the rate of clarification of the glass mass. Previously, the ratio of sodium sulfate and soda was 1:6, at present it is 1:20. This is dictated by the need to reduce the amount of SO 2 in flue gases. Sodium sulfate in the charge of sheet and colorless container glass is characterized by specific reactions.
For example, in a soda charge of sodium-calcium silicate glass, the following processes occur:
…………………………………………………………………………………………………… Temperature, °C
Formation of CaNa 2 (CO 3) 2 ……………………………………..……….below 600
CaNa 2 (CO 3) 2 + 2SiO 2 > CaSiO 3 + Na 2 SiO 3 + 2CO 2 ………………….. 600-830
Na 2 CO 3 + SiO 2 = Na 2 SiO 3 + CO 2 ………………………………………...720-830
The formation of fluxes and eutectics
CaNa 2 (CO 3) 2 - Na 2 CO 3 …………………………………………………..740-800
Melting double carbonate CaNa 2 (CO 3) 2 ……………………………813
Melting Na 2 CO 3 ………………………………………………………….855
Thus, the appearance of a melt (eutectic) in the mixture at a temperature below the melting point of soda.
The general scheme of thermal decomposition of sodium sulfate occurs according to the reaction:
Na 2 SO 4 (melt)> Na 2 O (melt) + SO 2 (gas) + 1/2 (O 2).
Final decomposition at temperatures above 1400 °C.
However, despite relatively low temperature melting of sodium sulfate (884 °C), the reaction with the charge components at this temperature is difficult. Therefore, a preliminary stage of "deoxidation" of sodium sulfate was introduced by interacting with a reducing agent. And then the first processes occurring in the mixture with sodium sulfate are presented as follows:
…………………………………………………………………………………………Temperature, °C
Na 2 SO 4 + 2C = Na 4 S + 2CO 3 ……………………………………..………..740-800
Na 2 S + CaCO 3 = CaS + Na 2 CO 3 …………………………………………...740-800
Eutectic formation:
Na 2 S - Na 2 SO 4 …………………….……………………………………....740
Na 2 S - NaCO 3 ………………………………………………….………….756
NaCO 3 - CaNa 2 (CO 3) 2 ………………………………………………………780
Na 2 SO 4 - CaCO 3 …………………………………………………………..795
Na 2 SO 4 - Na 2 SiO 3 ………………………………………………..………..865
Na 2 SO 4 + CaS + 2SiO 2 = Na 2 SiO 3 + CaSiO 3 + SO 2 + S……………….865
Na 2 SO 4 + Na 2 S + 2SiO 2 = 2Na 2 SiO 3 + SO 2 + S…………………………865
The eutectic in the sulfate mixture appears at the same temperature as in the soda mixture. However, when N 2 S appears, then in a mixture of Na 2 SO 4 + Na 2 S + SiO 2 it plays the role of a flux, the reaction begins at 500 ° C and the onset of the reaction Na 2 SO 4 + SiO 2 decreases to 650-700 ° C .
When sulfates are used as clarifiers, complex redox processes occur in glass mass, associated with the presence of several elements of variable valence in it, such as C, S, Fe. The quality of clarification depends on the correct selected amount of clarifier introduced into the mixture and the redox state (ORS) of the glass mass and mixture.
The use of sodium sulfate in the production of concrete.
Sodium sulfate is used as an additive in concrete to accelerate hardening in the early stages.
The optimal content of the sodium sulfate additive in the concrete mixture is within 1–2% of the mass of cement.
Sodium sulfate is introduced into the concrete mixture, as a rule, in the form of an aqueous solution of 10% concentration, with a density of 1.092 g/cm 3 . Therefore, to introduce 3.1 kg of salt into concrete in the form of a 10% solution per 1 m 3 of the mixture, it will be required: 3.1 / 0.1092 \u003d 28.4 liters. This amount of an aqueous solution of salt water contains: 1.092x28.4-3.1 = 27.9 liters. Thus, the amount of mixing water, taking into account the aqueous solution of the additive for preparing 1 m 3 of the concrete mix, will be: 155-27.9=127.1 l. Similar calculations are made with the introduction of additives in amounts of 1.5 and 2.0% by weight of cement.
The use of sodium sulfate for the accumulation of thermal energy.
Anhydrous sodium sulfate is not used for these purposes. For this, sodium sulfate decahydrate (Na 2 SO 4 10H 2 O), which is called Glauber's salt or mirabilite, is used. Minerals can be a source of mirabilite natural origin or the reaction of anhydrous sodium sulfate with water.
This method of thermal storage is based on phase transitions of various materials. By analogy with the "ice-water" system, in which the transition from one state to another occurs at 0 °C with the corresponding release (absorption) of heat, the melting of mirabilite in its own crystallization water occurs at 32.4 °C with heat absorption at the corresponding temperature V daytime and its subsequent isolation during crystallization at night. This creates the possibility of maintaining in greenhouses temperature regime, optimal for growing plants, protecting them from overheating during the day and from frost at night.
To reduce (increase) the air temperature by 10° in a greenhouse 3x6x3 m, taking into account the accumulation of heat in the soil and the material of the greenhouse, about 25 kg of mirabilite is needed.
Placement of salt in a greenhouse in several special relatively simple containers can provide a reduction in temperature overloads at night and during the period of maximum solar
activity. The use of a system with a water heat exchanger can significantly increase the efficiency of this method of accumulating heat (cold) not only in an unheated private, but also in an industrial heated greenhouse.
However, this way thermal energy storage has its own characteristics and disadvantages. The study of which is not yet fully completed.
One of the significant disadvantages of mirabilite, in addition to the tendency to supercooling, is the incongruent nature of melting, which results in separation of the solid and liquid phases with the precipitation of sodium sulfate heptahydrate. As a result, the enthalpy of the phase transition decreases with an increase in the number of "melting-crystallization" cycles and the heat transfer efficiency associated with the deposition of the solid phase on the heat transfer surface decreases. The reversibility of the phase transition can be stabilized by introducing heterogeneous additives into sodium sulfate, which act as crystallization centers.
The price of sodium sulfate favors its use in heat storage compositions.
The use of sodium sulfate for drying seeds.
Sodium sulfate is used for chemical drying of legume seeds before laying the seeds for storage. Before processing the seeds, their moisture content is determined. To reduce humidity, 1.3-1.5% (by weight) of sodium sulfate is taken for each percentage of moisture. Dried seeds can be stored until spring without separating the sodium sulfate. Seed germination does not decrease from this.
Receipt.
An industrial method for producing sodium sulfate is the interaction of NaCl with H 2 SO 4 in special "sulfate" furnaces at 500-550 ° C.
Sodium sulfate- it is colorless. crystals; known in four polymorphic modifications;
Physical Properties
refractive indices: smaller Np = 1.469, average Nm = 1.476, larger Ng = 1.481;
crystallizes from aqueous solutions above 32.384 ° C. In the range from -1.2 to 32.4 ° C, the decahydrate crystallizes, from -3.5 to 24.25 ° C, the metastable heptahydrate also crystallizes. solubility of anhydrous N.s. in water 21.9% by weight (25 °C). T. kip. sat. water solution(29.7% by weight N.s.) 102.88°C.
Poor sol. in water-alcohol environments; solution at 20 °C in ethanol 0.439% by weight, methanol-2.40%.
With K2SO4, Li2SO4 and a number of others forms continuous series solid solutions, with sulfates Sc and Y-double salts, with SrSO4 - eutectic.
Application
In the world a large number of sodium sulfate were previously used in the production of synthetic detergents CMC, but in many countries in last years there was a transition to concentrated (compact) washing powders, in which sulfate is either not used or used in small quantities. The second largest use of sodium sulfate is glass production. Also, this substance is used to obtain sulfate pulp, in the textile, leather industry and in non-ferrous metallurgy. In medicine and veterinary medicine, it was previously widely used as a saline laxative, and is also used as an ingredient in nasal washes.
Sodium sulfate (sodium salt of sulfuric acid or sodium sulfate) with the chemical formula Na2O4. It is a white or slightly yellowish powder, which is widely used in various industries.
Main characteristics:
- in water has the property of dissolving;
- explosion and fire safe chemical;
- dust-air mixture is not explosive;
- not combustible;
- does not cake;
- low hygroscopic;
- colorless crystals;
- temperature stability (32 degrees);
- anhydrous.
Today, sodium sulfate is used in many types of industry:
- in the manufacture of glass and wood processing;
- photographic view sodium sulfate is used in film and photography;
- in textile, paper, leather, metallurgical, light industry and non-ferrous metallurgy;
- to obtain sulfate pulp and viscose silk;
- V household chemicals(for example, as an additive to powders, detergents and cleaners, shampoos, toothpastes);
- in veterinary, pharmaceutical, medical (for example, as a nasal wash, as a saline laxative for poisoning, to cleanse the blood and stomach);
- in construction as a frost-resistant substance;
- as a chemical used in laboratories as a dehydrating agent.
It belongs to the third class of hazard of exposure to the human body. With strong heating, the container with chemical may explode. When working with this chemical, special clothing and dust masks are recommended for workers in production. Do not allow contact with eyes Airways and human skin. If it was not possible to avoid getting hit, then it is urgent to rinse the body parts with running water, and drip the eyes with a 3% solution of albucid.
Instruction
Because sulfate sodium is a salt formed by the strong base NaOH and the strong acid H2SO4, its solution has a pH close to neutral. That is, indicators such as litmus and phenolphthalein in this salt do not change color.
IN laboratory conditions, you can get sulfate sodium, acting with sulfuric acid on soda ash (sodium carbonate). The reaction goes to the end, because as a result coal is formed, which immediately decomposes into water and carbon dioxide:
H2SO4 + Na2CO3 = Na2SO4 + H2CO3
H2CO3 = H2O + CO2
Sodium sulfate is used in many industries. Mainly in the production of detergents (as one of the components), as well as in the production of glass. Sodium sulfate also finds application in the pulp and paper industry, in the production of textiles, leather processing, etc. In the laboratory, sodium sulfate is widely used to dry organic solvents. Can also be applied in Food Industry, as an additive, the code according to the international nomenclature is E514. still finds limited use in medicine and veterinary medicine.
Sulfate sodium(it is also sodium sulfate, the outdated name is “Glauber's salt”) has chemical formula Na2SO4. Appearance - colorless crystalline substance. Sulfate sodium widely distributed in nature in the form already mentioned " Glauber's salt”, which is a combination of this salt with ten water molecules: Na2SO4x10H2O. Minerals of a different composition are also found. Let's say there is whole line weights of salts similar in appearance, and the task was set: to determine which of them is sodium sulfate.
Instruction
First of all, remember that sulfate is a salt formed from a strong base (NaOH) and a strong acid (H2SO4). Therefore, its solution should have a pH of neutral (7). Dilute a small amount of each salt in water and use indicators and phenolphthalein to determine what is in each tube. Remember that litmus turns red in an acidic environment, and phenolphthalein becomes raspberry in an alkaline environment.
Set aside those samples in which the color of the indicators has changed - they definitely do not sodium sulfate. Substances whose solution pH is close to neutral will be subjected to a qualitative reaction to the sulfate ion. Alternatively, add a small amount of barium chloride solution to each sample. That sample, where a dense white precipitate instantly formed, probably contains this ion, because the following reaction took place: Ba2+ + SO42- = BaSO4.
It remains to be clarified whether, in addition to the sulfate ion, it also contained the ion sodium. Maybe it was potassium sulfate or lithium sulfate, for example. To do this, place a small amount of dry matter related to this sample in the burner flame. If you see a bright yellow color, it is probably an ion sodium. If the color is bright red - this is lithium, and dark purple - potassium.
