The sodium sulfate is an inorganic salt whose chemical formula is NatwoSW4. It consists of a white solid, present in three forms: anhydrous, the heptahydrate (scarcely available) and the decahydrate (which is known as Glaubert's salt); the latter is the most abundant form of sodium sulfate.
Sodium sulfate decahydrate, NatwoSW410HtwoOr, it was discovered in 1625 by Glaubert in the water of a spring, who named it sal mirabilis (miraculous salt) due to its medicinal properties.
Sodium sulfate has numerous applications in the textile and paper industry, as well as in the manufacture of glass. Its uses are extended to thermal applications, which include ambient heat supply and laptop cooling..
Sodium sulfate is a low toxicity compound and its harmful actions are mainly mechanical and non-chemical. For crystallographic reasons this salt, like its potassium counterpart, KtwoSW4, features lattice and polymorphic structures.
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The formula NatwoSW4 indicates at once that the Na ions in the salt crystals+ And so4two- they are in a 1: 2 ratio; that is, for every two Na cations+ there is an anion SO4two- interacting with them through electrostatic attraction (top image).
Of course, this applies to the NatwoSW4 anhydrous, no water molecules coordinated with sodium within the crystals.
Despite being a seemingly simple salt, its description is structurally complex. The NatwoSW4 presents polymorphism, having up to five crystalline phases: I, II, III, IV and V, whose transition temperatures are 180, 200, 228, 235 and 883 ºC, respectively.
Although there are no references to certify it, the NatwoSW4I must be the one with a hexagonal crystalline structure, denser compared to the orthorhombic NatwoSW4III, in whose crystals Na+ form tetrahedra (NaO4) and octahedra (NaO6) coordination; that is, it can be surrounded by four or six anions SO4two-.
Meanwhile, the monoclinic crystal structure of its most important hydrate, NatwoSW410HtwoOr, it is simpler. In it, it is practically the water molecules that interact or coordinate with Na+ in the octahedra Na (HtwoOR)6+, with the SO4two- just providing sufficient stability to the crystal so that it exists in the solid phase.
However, its melting point (32.38 ºC) much lower than that of the anhydrous salt (884 ºC) demonstrates how water molecules and their hydrogen bonds weaken the stronger ionic interactions in NatwoSW4.
-Sodium sulfate (IUPAC)
-Glauber's salt (decahydrate)
-Miraculous salt (decahydrate)
-Disodium sulfate.
142.04 g / mol (anhydrous)
322.20 g / mol (decahydrate)
White hygroscopic crystalline solid
Toilet
Bitter and salty
2,664 g / cm3 (anhydrous)
1,464 g / cm3 (decahydrate)
Note how the water molecules inside the crystals cause them to expand and, therefore, decrease their density..
884 ºC (anhydrous)
32.38 ºC (decahydrate)
1,429 ºC (anhydrous)
4.76 g / 100 ml (0 ºC)
13.9 g / 100 ml (20 ° C)
42.7 g / 100 ml (100 ° C)
All solubility values correspond to the anhydrous salt, which is quite soluble in water at all temperatures..
Solubility increases abruptly between 0ºC and 38.34ºC, observing that in this temperature range the solubility increases more than 10 times. However, from 32.38 ºC, solubility is independent of temperature..
It happens that at a temperature of 32.8 ºC, the sodium sulfate decahydrate dissolves in its own crystalline water. An equilibrium is thus reached between the decahydrate salt, the anhydrous salt and the saturated solution of sodium sulfate..
As long as the three-phase condition is maintained, the temperature will remain constant, which allows the temperature of the thermometers to be calibrated.
On the other hand, the solubilities for the heptahydrated salt are:
19.5 g / 100 ml (0 ºC)
44.0 g / 100 ml (20 ° C)
Note that at 20 ° C the heptahydrated salt is three times more soluble than the anhydrous one..
1,468 (anhydrous)
1.394 (decahydrate)
Stable under recommended storage conditions. Incompatible with strong acids and bases, aluminum and magnesium.
When heated to decomposition it emits toxic smoke of sulfur oxide and sodium oxide..
A 5% aqueous solution has a pH of 7.
Sodium sulfate dissociates in aqueous solution into 2 Na+ And so4two-, which allows the sulfate ion to combine with the Batwo+ to precipitate barium sulfate. Practically helps displace barium ions from water samples.
Sodium sulfate is converted to sodium sulfide by reacting at elevated temperatures with coal:
NatwoSW4 + 2 C => NatwoS + 2 COtwo
Glaubert's salt, NaSO4.10HtwoOr reacts with potassium carbonate to produce sodium carbonate.
Sodium sulfate is used in the manufacture of paper pulp. It is used in the production of Kraft paper, which does not contain lignin or is subjected to the bleaching process, which gives it great resistance. In addition, it is used in the manufacture of cardboard.
Used as a filler material for synthetic household detergents, being added to detergent to reduce surface tension.
It is used in glass making to reduce or eliminate the presence of small air bubbles in molten glass. Additionally, it eliminates the formation of slag during the refining process of the molten glass.
Sodium sulfate is used as a mordant, since it facilitates the interaction of dyes with the fibers of fabrics. Sodium sulfate decahydrate is used in the dye test.
In addition, sodium sulfate is used as a dye diluent and dye printing auxiliary agent; such as direct dyes, sulfur dyes, and other agents that promote cotton staining. It is also used as a retarding agent for direct silk dyes.
Sodium sulfate decahydrate is used as a laxative, since it is poorly absorbed in the intestine, and therefore remains in the lumen of the intestine, causing an increase in volume. This stimulates the increase in peristaltic contractions which induce the expulsion of intestinal contents..
Sodium sulfate is an antidote to control barium and lead salt poisoning. Glaubert's salt is effective for the elimination of certain excessively ingested medications; for example, paracetamol (acetoaminophen).
In addition, it is used to supply deficient electrolytes present in isoosmotic solutions..
Sodium sulfate, being an inert reagent, is used to remove water from solutions of organic compounds..
Sodium sulfate is used as a raw material for the production of numerous substances, including: sodium sulfide, sodium carbonate, and ammonium sulfate.
Sodium sulfate is obtained by mining extraction and by chemical reactions.
There are three ores or minerals that are exploited with commercial yield: thenardite (NatwoSW4), the mirabilite (NatwoSW410HtwoO) and glaubarite (NatwoSW4·Case4).
In Spain, the deposits of thenardite and mirabilite are exploited by underground mining of galleries and pillars. Meanwhile, the glauberite is obtained in the open, by means of large rafts that are placed on the mineral deposit.
The land is prepared with low intensity blasting to produce a porosity that allows the leaching of sodium sulfate. The production phase occurs with the sprinkler irrigation with fresh water of the glauberite, the leaching of which spreads downward..
The sodium sulfate brine is collected, leaving the calcium sulfate residue as filling..
Sodium sulfate is obtained during the production of hydrochloric acid by two processes: the Mannheim process and the Hardgreaves process.
It is carried out in large steel furnaces and with a 6 m steel reaction platform. The reaction occurs between sodium chloride and sulfuric acid:
2 NaCl + HtwoSW4 => 2 HCl + NatwoSW4
It involves the reaction of sodium chloride, sulfur oxide, oxygen, and water:
4 NaCl + 2 SOtwo + ORtwo + 2 htwoO => 4 HCl + NatwoSW4
Sodium sulfate is produced in the neutralization reaction between sodium hydroxide and sulfuric acid:
2 NaOH + HtwoSW4 => NatwoSW4 + HtwoOR
Sodium sulfate is a by-product of the production of numerous compounds. It is extracted from the liquid waste discharged during the production of viscose and cellophane. Also in the production of sodium dichromate, phenols, boric acid and lithium carbamate.
Sodium sulfate is considered a low toxicity compound. However, it may cause some harm to the person who uses it improperly..
For example, it can cause eye irritation, redness, and pain on contact. On the skin it can cause irritation and allergy in some people. Its ingestion can cause irritation of the digestive tract with nausea, vomiting and diarrhea. And finally, its inhalation produces irritation in the respiratory tract.
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