Sodium Sulfate - Definition, Structure, Uses, Preparation, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:41 PM IST

What is Sodium Sulfate?

Sodium sulfate (Na₂SO₄) is a sodium salt of sulfuric acid. Anhydrous sulphate is seen as a white crystalline solid which is also known as mineral thenardite, while decahydrate Na₂SO₄.10H₂O is known as Glauber salt or mirabilis.Na₂SO₄.7H₂O is converted to mirabilite when cooled. Mirabilite is a natural mineral decahydrate. About two-thirds of the total world's production of sodium sulfate is found in mirabilite.

This Story also Contains

What is Sodium Sulfate?
Features of Sodium Sulphate
Solubility of Sodium Sulphate
Use of Sodium Sulphate
Preparation of Sodium Sulfite
Sodium Sulfite Structures
Chemical Properties of Sodium Sulfite
Health Risks of Sodium Sulfite
Allergy to Sodium Sulfite

It is also produced from chemical process products such as hydrochloric acid production. In late 1625, Johann Rudolf Glauber discovered sodium sulfate in the Austrian water in the spring, when the hydrate form began to be known as Glauber's salt. Because of its medicinal properties, he named it sal mirabilis (miracle salt).

The crystals were used as a common laxative, until the 1900s. In reaction with the given potassium carbonate or potash, Glauber's salt was used as a raw material in the production of soda ash industries in the 18th century. By the nineteenth century, the demand for ash had increased too much, so the large Leblanc process that was used to produce synthetic sodium sulfate became one of the main means of the production of soda ash. At the level of food, the excretion is mainly urine. Sulfates are found in all body cells, with very high concentrations of connective tissue, bone and cartilage. Sulfates play a role in many important metabolic pathways, including those involved in metabolic processes.

There are two types of sodium sulphate

1.natural sodium sulphate and

2.synthetic sodium sulfate

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The Natural sodium sulfate is originally produced from naturally occurring bridges and crystalline deposits that are found in California and Texas. It is also found as part of salt marshes, such as the Great Salt Lake in Utah. Synthetic sodium sulfate is obtained as a product of various production processes. Both of these types of sodium sulfate have several important and useful systems in different consumer products. In a study of the top 50 basic biomarkers and inorganic products made in the United States, sodium sulfate was ranked 47th in terms of quantity produced.

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Sodium is one of the most abundant elements that is found in the Earth's crust and it ranks sixth. Sodium sulfate minerals are geologically small, especially in the post-glacial age. The compound Sodium sulfate is widespread and is commonly found in seawater and many salty or alkaline lakes. The economic storage of natural sodium sulfate is estimated at 3.3 billion tons worldwide. With global production of 2.6 million tons of natural sodium sulfate per year, goods are sufficient to meet the expectations of centuries. The given quantity of synthetic sodium sulfate also depends on the longevity of production firms that recover from the sulfate product. Drainage or ponds with no food areas and fed by spring water flowing over volcanic rocks containing sulphide minerals usually produce melted sulfur salts mixed with contact with the air to produce sulfates.

Features of Sodium Sulphate

Molecular Formula of sodium sulphate is Na₂SO₄

Molecular weight of sodium sulphate is 142.04gm / anhydrous, 322.20gm / decahydrate

Solid look of solid crystal

Smell of sodium sulphate is Odorless

Boiling point of sodium sulphate is 1429oC (anhydrous)

Flashpoint 800oC

Melting point of sodium sulphate is 884oC (anhydrous), 32.40C (decahydrate)

Density of sodium sulphate is known to be 2.664gm / ml (anhydrous), 1.464gm / ml (decahydrate)

Indicator indicator 1.468 (anhydrous), 1.394 (decahydrate)

Solubility of Sodium Sulphate

Soluble in water, glycerol and

hydrogen iodide and is insoluble internally

ethanol

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Use of Sodium Sulphate

Sodium sulfate is used to dry organic beverages.

Like filling out the laundry for household appliances.

As a fining agent that removes small air bubbles from the molten glass.

Glauber's salt, decahydrate,was also used as a laxative to remove various certain drugs like acetaminophen from the body.

What makes the windows more subdivided, of carpet remodeling, starch production, as an addition to cattle feed.

In the cleaning process and in the Kraft paper milling process.

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Preparation of Sodium Sulfite

1. In laboratories the sodium sulfite is always usually prepared from the reaction between gaseous sulfur dioxide (SO₂) and sodium hydroxide (NaOH). The chemical balance of this reaction is provided by

SO₂ + 2NaOH → Na₂SO₃ + H₂O

The dissolution of the NaOH reactor can be achieved by the incorporation of a few drops of concentrated H₂SO₄, which resulted in the release of SO₂ gas.

2. In industry, Na₂SO₃ is produced by the given reaction between sulfur dioxide solution and even sodium carbonate solution. Initially, sodium bisulfite (NaHSO₃) was formed. This compound now reacts with sodium carbonate or sodium hydroxide to produce a sodium sulfite product. Responses can be made to:

Na₂CO₃ + SO₂ → Na₂SO₃ + CO₂

Sodium Sulfite Structures

The molar weight of this element is 126,043 grams per mole.

The non-anhydrous sodium sulfite exists as a white, odorless solid that often weighs about 2.633 grams per cubic centimeter.

The heptahydrate form has a low density of 1.561 g / cm³.

When heated to 306.5K (33.4oC), heptahydrate absorbs water from the body. The non-anhydr form dissolves at a temperature of 500o

Sodium sulfite has no place to boil because it tends to rot at high temperatures.

It is soluble in water, its solubility is about 27g / 100mL.

The water-soluble structure of Na₂SO₃ has six sides and the heptahydrate crystals have a monoclinic structure.

Chemical Properties of Sodium Sulfite

When exposed to strong or weak acids, Na₂SO₃ begins to decompose, releasing gaseous sulfur dioxide.

Sodium sulfite reacts with aldehydes to produce bisulfite adducts. However, sulfonic acids are produced by their reaction with ketones.

Sodium sulfite solutions are connected to atmospheric oxygen, producing sodium sulfate.

This mixture is insoluble in ammonia and chlorine.

NCERT Chemistry Notes:

Health Risks of Sodium Sulfite

Sulfites are those compounds that contain sulfite ions which are usually composed of sodium (sodium sulfite) or even potassium (potassium sulfite). Sulfur releases an irritating gas sulfur dioxide, which acts as a protective and white agent. Also occurring naturally in other foods and in the human body, sulfites were added to certain foods to act as a natural antiseptic as they inhibit bacterial growth, preserve food color and extend shelf life. Sulfur-rich foods include wine, beer and dried fruit. They are also used to extract food starch, such as potato starch and are used in the production of certain food packaging materials such as cellophane.

Allergy to Sodium Sulfite

It is not yet clear why sulfites cause some people to react negatively but not to others. Sulfur dioxide is a non-irritating gas so it has been suggested that there should be less airways as one possible option, as most people with sulfite allergies show symptoms such as asthma.

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Frequently Asked Questions (FAQs)

1. 1.What are uses of sodium sulfite ?

Sodium sulfite is usually used as a sulfonation and sulfomethylation agent in some of the chemical manufacturing industries. It is also used in the production of sodium thiosulfate. This combination has many other important functions, including froth ores flotation, oil retrieval, food preservatives, and coloring.

2. 2. Is sodium sulfate an acid base or salt?

Sodium sulfate is a neutral salt, which forms aqueous solutions with pH of 7.

3. 3. What will happen if sodium sulphate is reacted with barium chloride?

Sodium sulphate reacts with barium chloride in a double reaction of migration to make barium sulphate and sodium chloride. The chemical equilibrium of this reaction is provided by:

BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl

This reaction occurs because sodium sulfate is an ionic sulphate bound by electricity.

4. 4.Make a brief note of the dissolution of sodium sulfate in water

At a temperature of 0 degrees Celsius, the dissolution of sodium sulfate in water is 47.6 grams per liter. At a temperature of 20 degrees Fahrenheit [20 ° C], its solubility rises sharply to 139 grams per liter. Finally, at a temperature of 100 degrees Celsius, the dissolution of sodium sulfate in water is about 427 grams per liter.

5. 5.How can sodium sulphate be prepared?

Sodium sulphate can be prepared by the Mannheim process, provided by the following solution:

H₂SO₄ + 2NaCl → Na₂SO₄ + 2HCl

It can also be repaired through the Hargreaves process, as shown below:

O₂ + 2H₂O + 4NaCl + 2SO₂ → 4HCl + 2Na₂SO₄

6. How does the structure of sodium sulfate contribute to its properties?

The structure of sodium sulfate consists of Na+ ions and SO4^2- ions arranged in a crystal lattice. This ionic structure contributes to its high melting point, solubility in water, and electrical conductivity when dissolved. The strong electrostatic forces between the oppositely charged ions result in a stable, solid compound at room temperature.

7. What is the difference between anhydrous sodium sulfate and Glauber's salt in terms of their physical appearance?

Anhydrous sodium sulfate (Na2SO4) appears as a white, crystalline solid. It's hygroscopic and tends to absorb moisture from the air. Glauber's salt (Na2SO4·10H2O), on the other hand, forms large, transparent, colorless crystals. These crystals can effloresce (lose water) in dry air, forming a white powder on the surface.

8. How does the crystal structure of anhydrous sodium sulfate differ from its hydrated forms?

Anhydrous sodium sulfate (thenardite) has a different crystal structure compared to its hydrated forms. The anhydrous form typically crystallizes in an orthorhombic system, while the decahydrate (mirabilite) forms monoclinic crystals. These structural differences result in distinct physical properties, such as density and solubility, between the anhydrous and hydrated forms.

9. How does the pH of a sodium sulfate solution compare to that of sodium chloride?

A solution of sodium sulfate is slightly basic (pH > 7), while a sodium chloride solution is neutral (pH = 7). This is because the sulfate ion (SO4^2-) is the conjugate base of a weak acid (sulfuric acid's second deprotonation), and it undergoes slight hydrolysis in water. In contrast, chloride ions do not hydrolyze significantly.

10. Why is sodium sulfate sometimes used in solar energy storage systems?

Sodium sulfate is used in some solar energy storage systems due to its phase change properties. The transition between its anhydrous and hydrated forms (particularly the decahydrate) involves absorbing or releasing significant amounts of heat. This property can be exploited to store thermal energy from solar collectors during the day and release it at night or during cloudy periods.

11. How is sodium sulfate prepared industrially?

Industrially, sodium sulfate is primarily produced as a byproduct of other chemical processes. One common method is the Mannheim process, where sodium chloride reacts with sulfuric acid to produce sodium sulfate and hydrogen chloride. It's also obtained as a byproduct in the production of hydrochloric acid from sodium chloride and sulfuric acid, and in the manufacture of various other chemicals like sodium dichromate and cellulose.

12. Why does anhydrous sodium sulfate readily absorb water from the air?

Anhydrous sodium sulfate is hygroscopic, meaning it readily absorbs water from the air. This is due to the strong attraction between the ionic sodium sulfate and polar water molecules. The absorption of water leads to the formation of hydrates, particularly sodium sulfate decahydrate (Na2SO4·10H2O), also known as Glauber's salt.

13. How does the solubility of sodium sulfate change with temperature?

The solubility of sodium sulfate in water exhibits an unusual behavior with temperature. Unlike most salts, its solubility increases with temperature up to about 32.4°C, then decreases as the temperature rises further. This phenomenon, known as retrograde solubility, is due to the formation and decomposition of hydrates at different temperatures.

14. How does sodium sulfate affect the boiling point of water?

Like other dissolved salts, sodium sulfate increases the boiling point of water. This is another colligative property of solutions, where the presence of dissolved particles interferes with the escape of water molecules into the vapor phase. The boiling point elevation is proportional to the concentration of the dissolved sodium sulfate.

15. How does sodium sulfate interact with calcium ions in solution?

When sodium sulfate is mixed with a solution containing calcium ions, it can form calcium sulfate (CaSO4). Calcium sulfate has low solubility in water and may precipitate out of the solution. This reaction is the basis for using sodium sulfate to test for the presence of calcium ions in qualitative analysis and can also be a concern in industrial processes where calcium sulfate scale formation is undesirable.

16. What is the environmental impact of sodium sulfate use and disposal?

Sodium sulfate is generally considered to have a low environmental impact. It's not toxic to aquatic life at typical concentrations and doesn't bioaccumulate. However, large discharges can affect the salinity of freshwater ecosystems. In soil, it can contribute to salination if present in high concentrations. Proper disposal and management are important to minimize potential environmental effects.

17. How does sodium sulfate act as a drying agent?

Sodium sulfate acts as a drying agent due to its hygroscopic nature. When added to organic solvents or other substances containing water, it absorbs the water molecules, forming hydrates. This property makes it useful in laboratory settings for drying organic solvents or removing water from reaction mixtures.

18. Why is sodium sulfate used in detergents?

Sodium sulfate is used in detergents as a filler and to prevent caking. It helps to standardize the powder detergent's density, improve its free-flowing properties, and enhance the overall cleaning effectiveness. Additionally, it doesn't interfere with the cleaning action of other ingredients and is relatively inexpensive.

19. How does sodium sulfate contribute to glass production?

In glass production, sodium sulfate acts as a fining agent. It helps remove small air bubbles from the molten glass, resulting in a clearer, more uniform product. During the heating process, sodium sulfate decomposes to release sulfur dioxide gas, which helps to remove other dissolved gases and impurities from the glass melt.

20. What is the role of sodium sulfate in the Kraft process for paper production?

In the Kraft process for paper production, sodium sulfate is used as a makeup chemical to compensate for losses in the process chemicals. It's converted to sodium sulfide during the recovery process, which then participates in the breakdown of lignin in wood chips. This helps maintain the chemical balance in the pulping process and ensures efficient paper production.

21. How does sodium sulfate impact the freezing point of water?

When dissolved in water, sodium sulfate lowers the freezing point of the solution. This is due to the colligative properties of solutions, where the presence of dissolved particles interferes with the formation of ice crystals. However, the effect is less pronounced compared to some other salts like sodium chloride, which is why sodium chloride is more commonly used for de-icing.

22. What is sodium sulfate and why is it classified as an s-block compound?

Sodium sulfate (Na2SO4) is an inorganic salt composed of sodium cations (Na+) and sulfate anions (SO4^2-). It's classified as an s-block compound because sodium, its metal component, is found in the s-block of the periodic table. S-block elements have their valence electrons in the outermost s orbital, which gives them characteristic properties like high reactivity and tendency to form ionic compounds.

23. What is Glauber's salt and how is it related to sodium sulfate?

Glauber's salt is the common name for sodium sulfate decahydrate (Na2SO4·10H2O). It's the hydrated form of sodium sulfate, containing ten water molecules per formula unit. Glauber's salt forms when anhydrous sodium sulfate absorbs water from the air or when a saturated solution of sodium sulfate is cooled below 32.4°C.

24. What is mirabilite and how is it related to sodium sulfate?

Mirabilite is a naturally occurring hydrated form of sodium sulfate, with the chemical formula Na2SO4·10H2O. It's the same as Glauber's salt but refers specifically to the mineral form found in nature. Mirabilite occurs in salt lakes and hot springs and can dehydrate to form thenardite (anhydrous sodium sulfate) under dry conditions.

25. How does sodium sulfate affect the viscosity of aqueous solutions?

Sodium sulfate, like many electrolytes, increases the viscosity of water when dissolved. This is due to the formation of hydration shells around the ions, which increases the effective size of the particles in solution. The increased viscosity can affect fluid dynamics in various applications, from industrial processes to laboratory techniques like gel electrophoresis.

26. What is the significance of sodium sulfate in the production of sodium carbonate?

Sodium sulfate plays a crucial role in the Leblanc process, an older method for producing sodium carbonate (soda ash). In this process, sodium sulfate is reduced to sodium sulfide, which then reacts with calcium carbonate to form sodium carbonate. While the Leblanc process is largely obsolete today, it was historically significant in the development of the chemical industry.

27. Why is sodium sulfate sometimes used in the textile industry?

In the textile industry, sodium sulfate is used as a leveling agent in dyeing processes. It helps to ensure even distribution of dye molecules on the fabric by modifying the rate of dye uptake. This results in more uniform coloration and prevents streaking or blotching, especially when dyeing cotton or wool with direct or acid dyes.

28. Why is sodium sulfate sometimes used in the production of detergent powders?

In detergent powder production, sodium sulfate serves multiple purposes. It acts as a bulking agent, helping to standardize the density and improve the flow properties of the powder. It also aids in the spray-drying process used to produce powder detergents, helping to control moisture content and prevent caking. Additionally, it doesn't interfere with the cleaning action of the detergent's active ingredients.

29. How does the presence of sodium sulfate affect the freezing of water in comparison to pure water?

The presence of dissolved sodium sulfate lowers the freezing point of water. This is a colligative property, meaning it depends on the number of dissolved particles rather than their nature. When sodium sulfate dissolves, it separates into sodium and sulfate ions, effectively increasing the number of particles in solution. This interferes with the formation of ice crystals, requiring a lower temperature for freezing to occur compared to pure water.

30. What role does sodium sulfate play in the production of kraft paper?

In the kraft paper production process, sodium sulfate is used as a makeup chemical to replenish the sodium and sulfur lost during the pulping and recovery cycles. It's added to the chemical recovery system where it's reduced to sodium sulfide, which then participates in the breakdown of lignin in wood chips. This helps maintain the chemical balance in the process and ensures efficient pulp production.

31. How does the solubility of sodium sulfate compare in water and organic solvents?

Sodium sulfate is highly soluble in water due to its ionic nature and the ability of water molecules to solvate the sodium and sulfate ions. In contrast, it's generally insoluble in most organic solvents. This difference in solubility is due to the polar nature of water versus the typically non-polar nature of organic solvents. The high solubility in water and insolubility in organic solvents make sodium sulfate useful as a drying agent for organic liquids.

32. What is the principle behind using sodium sulfate in phase change materials for thermal energy storage?

The use of sodium sulfate in phase change materials for thermal energy storage is based on its ability to absorb and release large amounts of heat during phase transitions. Specifically, the transition between anhydrous sodium sulfate and its decahydrate form (Glauber's salt) involves a significant enthalpy change. When heated, the hydrated form melts and releases water, absorbing heat in the process. When cooled, it rehydrates and releases this stored heat, making it useful for storing and releasing thermal energy in solar applications.

33. How does sodium sulfate affect the conductivity of its aqueous solutions?

Sodium sulfate, being an ionic compound, increases the electrical conductivity of water when dissolved. The sodium and sulfate ions are mobile charge carriers in the solution. The conductivity increases with the concentration of sodium sulfate, up to a certain point. However, at very high concentrations, ion-ion interactions can actually decrease the mobility of the ions, leading to a less than proportional increase in conductivity.

34. Why is sodium sulfate sometimes used in the preservation of wood?

Sodium sulfate is used in some wood preservation techniques, particularly in combination with other chemicals. It can help to reduce the hygroscopicity of wood, making it less prone to absorbing moisture from the air. This can help prevent swelling and shrinking of the wood, which can lead to cracking or warping. Additionally, in some treatments, it can help to fix other preservative chemicals within the wood structure.

35. How does the presence of sodium sulfate affect the surface tension of water?

The addition of sodium sulfate to water generally increases the surface tension of the solution. This is because the strong interactions between the ions and water molecules at the surface create a stronger "skin" effect. However, the increase is usually less pronounced than with some other salts. This property can affect processes like droplet formation and wetting behavior, which are important in various industrial and natural processes.

36. What is the difference between sodium sulfate and sodium bisulfate?

Sodium sulfate (Na2SO4) and sodium bisulfate (NaHSO4) are different compounds with distinct properties. Sodium sulfate contains the sulfate ion (SO4^2-), while sodium bisulfate contains the bisulfate ion (HSO4^-). Sodium sulfate is neutral to slightly basic in solution, whereas sodium bisulfate is acidic. Sodium bisulfate is often used as a pH reducer, while sodium sulfate is used more for its drying and bulking properties.

37. How does sodium sulfate impact the taste of mineral water?

Sodium sulfate can contribute to the taste of mineral water, although its effect is generally less pronounced than some other minerals. In low concentrations, it may impart a slightly salty taste. At higher concentrations, it can give water a bitter or astringent taste. The presence of sodium sulfate in mineral water can also affect the perception of other taste components and the overall mouthfeel of the water.

38. What is the role of sodium sulfate in some types of cement?

In cement production, sodium sulfate can be used as a setting regulator. It affects the hydration process of cement, particularly the reaction of tricalcium aluminate with water. By controlling this reaction, sodium sulfate helps to prevent flash setting (too rapid hardening) and can improve the workability of the cement paste. It can also influence the final strength and durability of the cement.

39. How does sodium sulfate compare to magnesium sulfate in terms of their uses as drying agents?

Both sodium sulfate and magnesium sulfate (Epsom salt) can be used as drying agents, but they have different properties. Anhydrous sodium sulfate is more commonly used for drying organic solvents because it's effective and doesn't form a separate layer with the solvent. Magnesium sulfate is often preferred for drying organic reaction mixtures because it's less basic and less likely to catalyze side reactions. Magnesium sulfate also forms distinct hydrates that make it easy to visually confirm when it's saturated with water.

40. Why is sodium sulfate sometimes added to cat litter?

Sodium sulfate is sometimes added to cat litter to help control odors. It can act as a desiccant, helping to absorb moisture from the litter and feces, which can reduce bacterial growth and associated odors. Additionally, in some formulations, it may help to clump the litter when wet, making it easier to scoop and maintain. The use of sodium sulfate in cat litter takes advantage of its hygroscopic properties and its relative safety for pets.

41. How does the presence of sodium sulfate affect the crystallization of other salts in solution?

The presence of sodium sulfate can affect the crystallization of other salts in solution through a phenomenon known as the "common ion effect." If another salt containing either sodium or sulfate ions is present, the solubility of that salt may be reduced due to the increased concentration of the common ion. This can lead to earlier precipitation or changes in crystal morphology. Additionally, sodium sulfate can act as a nucleation site for the crystallization of other compounds in some cases.

42. What is the significance of sodium sulfate in the production of glass?

In glass production, sodium sulfate serves as a fining agent and a flux. As a fining agent, it helps to remove small bubbles from the molten glass, resulting in a clearer final product. During heating, sodium sulfate decomposes to release sulfur dioxide gas, which helps to remove other dissolved gases. As a flux, it lowers the melting point of the glass mixture, making the production process more energy-efficient. It also contributes sodium to the glass composition, which affects properties like thermal expansion and chemical durability.

43. How does sodium sulfate interact with proteins in solution?

Sodium sulfate can interact with proteins in