The Story of Washing Soda (Na2CO3) - Solvay Process, Properties, Structure, Uses, FAQs

Q: What is washing soda?

Washing soda, Na 2 CO 3 .10H 2 O is an inorganic compound with many industrial and household uses. It also has the name soda ash since it was prepared from the ashes of plants and by burning baking soda in an oven. Washing soda as the name itself suggests it has a very important use in washing purposes. When washing soda comes in contact with dirt and greasy components it will convert these water-insoluble substances into water-soluble components and can be easily removed by rinsing with water. Thereby made the cleaning process easy. Washing soda is prepared in large quantities by the process named Solvay.

The Story of Washing Soda (Na2CO3) - Solvay Process, Properties, Structure, Uses, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:52 PM IST

The Story of Washing Soda Na₂CO₃.10H₂O

Sodium carbonate is the chemical name of washing soda is a white, odorless powder mainly used for washing purposes. Washing soda has many applications from household uses to industrial applications. It is basically an alkaline compound with a high basic character and has the ability to remove dirt from the clothes during washing. The chemical formula of washing soda is Na₂CO₃.10H₂O. Washing soda is a hygroscopic compound that can absorb water from the moisture present in the air.

This Story also Contains

The Story of Washing Soda Na2CO3.10H2O
What is Solvay Process?
Properties of washing soda
Uses of washing soda
Structure of Sodium Carbonate

It also has the name soda ash since sometimes it is made from the ashes of plants and also it is made by placing baking soda in the oven. And it is the hydrated salt of the chemical compound sodium carbonate. The alkalinity of washing soda can be tested using litmus paper, as the solution of washing soda turns the red litmus to blue. Washing soda contains 10 molecules of water if this water is not present it is given the name sodium carbonate anhydrate. The formula for which is Na₂CO₃. The sodium carbonate decahydrate formula is Na₂CO₃.10H₂O. Na₂CO₃.10H₂Ochemical name is sodium carbonate decahydrate.

Figure showing image of washing soda

Due to the presence of 10 water molecules washing soda has also another name that is sodium carbonate decahydrate. The elements present in washing soda are two sodium and one carbonate ion and is an ionic compound. Because the bond present in them is an ionic bond. The molar mass of washing soda is 106 grams per mole with a density of 2.54 grams per centimeter cube. as the compound is alkaline the taste of washing soda is an alkaline taste with a greyish white color. The melting point of washing soda is 851 degrees Celsius and the boiling point of 1600 degrees Celsius. The compound is a stable compound only at ordinary temperature if the temperature is high the compound dries out that is the water molecules present in them got dehydrated.

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What is Solvay Process?

Solvay process is a process that is used for manufacturing washing soda. It is a huge process as it requires four steps to manufacture the washing soda. The process is simple but it includes many steps. And care must be given in order to be free from contamination.

Things required for the production of washing soda

1. Sodium chloride

2. Limestone

3. Ammonia gas

The four steps involved in the manufacture of washing soda are described below.

1. Brine purification

2. Sodium hydrogen carbonate formation

3. Sodium carbonate formation

4. Ammonia recovery

Step1: Brine purification

The first step is the production of brine, which is the saturated solution of sodium chloride. The obtained brine is then concentrated by the evaporation process and the impurities present in them are removed by precipitation. The purification of brine is very important as it is very important to prevent the presence of impurities in the final product that is washing soda. When the impurities are removed the brine solution is filtered and allowed to pass the ammonia tower for dissolving the ammonia. When the purification is completed the brine is then allowed into contact with the ammonia gas.

Step2: Sodium hydrogen carbonate formation

The brine is now ammoniated and hydrogen carbonate is precipitated by slowing the brain into contact with carbon dioxide. The following is the reaction taking place for the formation of sodium hydrogen carbonate.

NH₃(aq)+CO₂(g)+NaCl(aq)+H₂O→NaHCO₃(s)+NH₄Cl(aq)

Step3: Sodium carbonate formation

The obtained sodium hydrogen carbonate is treated at 300 degrees celsius to produce the sodium carbonate. The following equation shows the reaction taking place in the formation of sodium carbonate.

2NaHCO₃→Na₂CO₃+CO₂+H₂O

Carbon dioxide is formed as a by-product and it then recycles the back for the formation of sodium hydrogen carbonate. Now the obtained sodium carbonate undergoing recrystallization to form the washing soda is also called a basic salt.

Step4: Ammonia recovery

By treating calcium hydroxide with ammonium chloride the ammonia can be easily recovered. The obtained ammonia can be recycled back for the Solvay process. And calcium chloride is obtained as a byproduct. The following equation shows the recovery of ammonia.

NH₄Cl+Ca(OH)₂→2NH₃+CaCl₂+H₂O

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Properties of washing soda

Washing soda is a white crystalline solid mainly existing in the decahydrate form. It is basic in character. In the presence of heat losses water molecules and form an anhydrate compound called sodium carbonate which also has industrial applications. The reaction taking place is

Na₂CO₃.10H₂O → Na₂CO₃+10H₂O

Washing soda is soluble in water and is alkaline in nature that it turns red litmus to blue. Washing soda and baking soda are different although they sound similar. Baking soda is sodium bicarbonate and it can be used for removing laundry odor. Washing soda is used for cleaning clothes. Washing soda removes dirt and grease from the clothes by converting the dirt and greasy components into water-soluble products that can be easily then washed away upon rinsing with water.

Also, students can refer,

Uses of washing soda

Washing soda is used for cleaning purposes in the household and also for industrial uses.
It has much application in many industrial fields like paper, textile, soap, detergent, etc.
It can be used for softening hard water, both temporary and permanent hardness can be removed.
For the manufacture of glass washing soda is one of the important components.
For the laundry purpose washing soda is one of the important agents.
For the manufacture of borax washing soda is used.
For the deep cleaning of washing machines washing soda is used.
Washing soda together with boiling water can be used for unclogging drains.

Structure of Sodium Carbonate

Sodium carbonate contains two sodium cations with a charge of +1, and it is surrounded above the anion carbonate. The bond present on them is ionic. The below figure shows the structure of sodium carbonate.

Figure Structure of sodium carbonate

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NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. What is the chemical formula of washing soda?

Na₂CO₃.10H₂O

2. The washing soda is also known as?

Soda ash. Since it is prepared from the ashes of plants and also by the burning of baking soda by placing them on the oven washing soda got another name as soda ash.

3. What is washing soda?

Washing soda, Na₂CO₃.10H₂O is an inorganic compound with many industrial and household uses. It also has the name soda ash since it was prepared from the ashes of plants and by burning baking soda in an oven. Washing soda as the name itself suggests it has a very important use in washing purposes. When washing soda comes in contact with dirt and greasy components it will convert these water-insoluble substances into water-soluble components and can be easily removed by rinsing with water. Thereby made the cleaning process easy. Washing soda is prepared in large quantities by the process named Solvay.

4. washing soda is acid or base?

Washing soda is a base, the reason is when washing soda is dissolved in water the compound dissociates into its respective ions as sodium hydroxide and the weak acid, carbonic acid. And also the solution turns the red litmus to blue which is the indication of basic character.

5. What is Na2CO3 compound name?/ Write na2co3 compound name.

Sodium carbonate.

6. What is the pH of washing soda?

11.6 is the pH of washing soda and is a base.

7. What is Na2CO3.10H2O chemical name?

Sodium carbonate decahydrate.

8. How is washing soda prepared?

Washing soda is prepared by the process named Solvay process. It is a process involving four steps but it is a simple process. Brine purification, Sodium hydrogen carbonate formation, Sodium carbonate formation, and Ammonia recovery are the four steps involved in the Solvay process.

9. What is the color of washing soda?

Greyish white color.

10. Why is washing soda considered a basic substance?

Washing soda is considered basic because when dissolved in water, it produces hydroxide ions (OH-). The carbonate ion (CO3^2-) reacts with water to form bicarbonate (HCO3-) and hydroxide ions, increasing the pH of the solution.

11. How does the solubility of washing soda change with temperature?

The solubility of washing soda increases significantly with temperature. This property is unusual for most solids dissolved in water. As the temperature rises, more washing soda can dissolve, making hot water more effective for cleaning with washing soda. This temperature-dependent solubility is also important in industrial crystallization processes.

12. How does the hydration of washing soda affect its properties?

Washing soda can exist in anhydrous (Na2CO3) and hydrated forms (e.g., Na2CO3·10H2O). The hydrated form has water molecules incorporated into its crystal structure, which affects properties like solubility and melting point. The hydrated form is less dense and more soluble in water than the anhydrous form.

13. How does washing soda interact with acids?

Washing soda reacts with acids in a neutralization reaction. The carbonate ion (CO3^2-) from washing soda accepts protons from the acid, forming carbonic acid (H2CO3), which then decomposes into water and carbon dioxide. This reaction makes washing soda useful for neutralizing acidic spills or adjusting pH in various applications.

14. How does washing soda contribute to pH regulation in swimming pools?

Washing soda helps regulate pH in swimming pools by increasing alkalinity. When added to water, it forms hydroxide ions, raising the pH. This helps counteract the acidifying effects of chlorine and prevents rapid pH fluctuations, maintaining a stable, slightly alkaline environment that is comfortable for swimmers and effective for disinfection.

15. What is the chemical formula of washing soda, and what does it tell us about its composition?

The chemical formula of washing soda is Na2CO3. This formula tells us that each molecule of washing soda contains two sodium ions (Na+) and one carbonate ion (CO3^2-).

16. How does the structure of washing soda contribute to its properties?

The structure of washing soda consists of sodium ions and carbonate ions arranged in a crystal lattice. This ionic structure gives washing soda its high melting point, solubility in water, and ability to conduct electricity when dissolved, which are characteristic properties of ionic compounds.

17. What is the crystal structure of anhydrous washing soda, and how does it differ from its hydrated form?

Anhydrous washing soda (Na2CO3) has a monoclinic crystal structure at room temperature. In contrast, the most common hydrated form, washing soda decahydrate (Na2CO3·10H2O), has a more complex structure with water molecules incorporated into the crystal lattice. This hydrated form has a lower density and different physical properties compared to the anhydrous form, including a lower melting point and higher solubility in water at room temperature.

18. What is the significance of washing soda in the context of acid-base chemistry?

In acid-base chemistry, washing soda is an important example of a base. It demonstrates how a salt of a strong base (sodium hydroxide) and a weak acid (carbonic acid) can itself act as a base. The carbonate ion from washing soda can accept protons from water, producing hydroxide ions and thus increasing pH. This makes washing soda a useful tool for teaching and understanding acid-base reactions and buffer systems.

19. What safety precautions should be taken when handling washing soda?

When handling washing soda, one should wear gloves to protect the skin from irritation, as it's alkaline and can cause dryness or burns. Eye protection is also recommended to prevent eye irritation or damage. Avoid inhaling the dust, as it can irritate the respiratory system. Always store it in a sealed container out of reach of children and pets.

20. Why is washing soda sometimes called soda ash?

Washing soda is called soda ash because it was historically obtained from the ashes of certain plants, particularly those growing in sodium-rich soils or marine environments. These plants would absorb sodium from the soil, and when burned, their ashes contained sodium carbonate.

21. What is the relationship between washing soda and the carbon cycle?

Washing soda (sodium carbonate) is part of the carbon cycle. In the Solvay process, CO2 is captured from limestone calcination and used to produce sodium bicarbonate, which is then converted to washing soda. When washing soda reacts with acids, it releases this CO2 back into the atmosphere. Understanding this cycle is important for assessing the carbon footprint of washing soda production and use.

22. What is the role of washing soda in the production of sodium bicarbonate?

Washing soda is a key intermediate in the production of sodium bicarbonate (baking soda) in the Solvay process. Carbon dioxide is bubbled through a solution of sodium chloride and ammonia, forming sodium bicarbonate. Some of this sodium bicarbonate is then heated to produce washing soda, while the rest is purified for use as baking soda.

23. How does washing soda affect the hardness of water, and what are the implications for soap efficiency?

Washing soda reduces water hardness by precipitating calcium and magnesium ions as insoluble carbonates. This process, known as softening, has significant implications for soap efficiency. In hard water, these ions form insoluble soap scum, reducing cleaning effectiveness. By removing these ions, washing soda allows soap to lather more easily and clean more effectively, reducing the amount of soap needed.

24. What is the significance of washing soda in the context of green chemistry?

In green chemistry, washing soda is significant as a relatively benign and sustainable chemical. Its production through the Solvay process uses common, non-toxic raw materials and recycles key components. Washing soda itself is biodegradable and non-toxic in normal concentrations. Its use can often replace more harmful chemicals in cleaning and industrial processes, aligning with principles of green chemistry such as designing safer chemicals and processes.

25. How does washing soda soften water?

Washing soda softens water by precipitating calcium and magnesium ions, which cause water hardness. The carbonate ions from washing soda react with these metal ions to form insoluble carbonates, effectively removing them from the water.

26. How does washing soda remove grease stains?

Washing soda removes grease stains through saponification. The alkaline nature of washing soda reacts with fatty acids in grease to form soap, which can then be washed away with water. Additionally, its high pH helps to break down and dissolve oily substances.

27. What role does washing soda play in the manufacture of glass?

In glass manufacturing, washing soda (sodium carbonate) serves as a flux, lowering the melting point of silica sand. It also provides the sodium ions necessary for creating soda-lime glass, the most common type of glass. The sodium helps to make the glass more workable and reduces its melting temperature.

28. What is washing soda, and why is it called that?

Washing soda is the common name for sodium carbonate (Na2CO3). It's called "washing soda" because it has been used historically as a water softener and cleaning agent in laundry and household cleaning applications due to its ability to remove grease and stains.

29. What is the difference between washing soda (Na2CO3) and baking soda (NaHCO3)?

While both are sodium-based compounds, washing soda (Na2CO3) is sodium carbonate, while baking soda (NaHCO3) is sodium bicarbonate. Washing soda is more alkaline and a stronger cleaning agent, while baking soda is milder and often used in cooking.

30. How does the Solvay process produce washing soda?

The Solvay process produces washing soda through a series of reactions involving ammonia, carbon dioxide, and salt brine. The key steps are: (1) Ammonia is dissolved in brine, (2) Carbon dioxide is bubbled through this solution, forming sodium bicarbonate, (3) Sodium bicarbonate is then heated to produce sodium carbonate (washing soda).

31. Why is the Solvay process considered more environmentally friendly than previous methods of producing washing soda?

The Solvay process is more environmentally friendly because it uses readily available and relatively harmless raw materials (salt, limestone, and ammonia). It also recycles ammonia in the process, reducing waste. Previous methods, like the Leblanc process, produced harmful byproducts and were more polluting.

32. What is the significance of washing soda in the history of industrial chemistry?

Washing soda played a crucial role in the development of industrial chemistry. The search for efficient methods to produce it led to the development of the Leblanc process and later the Solvay process, which were pivotal in the growth of the chemical industry. These processes also drove advancements in chemical engineering and large-scale production techniques.

33. What is the environmental impact of washing soda production and use?

While the Solvay process for producing washing soda is relatively environmentally friendly, it still has some impacts. These include energy consumption and CO2 emissions from limestone calcination. However, washing soda itself is biodegradable and non-toxic to aquatic life in normal concentrations. Its use can reduce the need for harsher chemicals in cleaning and industrial processes.

34. How does washing soda contribute to the circular economy?

Washing soda contributes to the circular economy in several ways. It's produced from abundant, natural materials and can be recycled in many industrial processes. Its use in water treatment and cleaning reduces the need for harsher chemicals. In the Solvay process, ammonia is recycled, minimizing waste. These factors make washing soda a relatively sustainable chemical in industrial and domestic use.

35. Why is washing soda used in the kraft paper process?

In the kraft paper process, washing soda is used to help break down lignin, the complex polymer that binds cellulose fibers in wood. The alkaline nature of washing soda helps to separate these fibers, making the pulping process more efficient. It also aids in the recovery of chemicals used in the process.

36. What is the role of washing soda in water treatment?

In water treatment, washing soda is used for pH adjustment and softening. It can raise the pH of acidic water and precipitate hardness-causing minerals like calcium and magnesium. This helps protect pipes from corrosion and improves the effectiveness of other water treatment processes.

37. How does washing soda compare to other alkaline cleaning agents?

Washing soda is a moderately strong alkaline cleaner, stronger than baking soda but not as strong as lye (sodium hydroxide). It's effective at removing grease and stains but gentler on surfaces than stronger alkalis. Its relatively low cost and environmental friendliness make it a popular choice for many cleaning applications.

38. How does washing soda affect the freezing point of water?

Washing soda, like other solutes, lowers the freezing point of water when dissolved in it. This is due to the colligative properties of solutions. The sodium and carbonate ions interfere with the formation of ice crystals, requiring a lower temperature for freezing to occur. This property can be useful in certain industrial or de-icing applications.

39. How does washing soda interact with metals?

Washing soda can react with some metals, particularly in the presence of moisture. It can cause corrosion in metals like aluminum, zinc, and tin. However, it's generally less corrosive than stronger alkalis. In some cases, this reactivity is useful, such as in removing oxidation from metals or in certain metallurgical processes.

40. What is the role of washing soda in photography?

In traditional film photography, washing soda is used in the developing process. It acts as an alkali in developer solutions, helping to activate the developing agents. It can also be used in stop baths to neutralize acidic developer chemicals and in fixing baths to remove undeveloped silver halides from the film or paper.

41. How does washing soda affect the surface tension of water?

Washing soda reduces the surface tension of water. This is because the sodium and carbonate ions interfere with the hydrogen bonding between water molecules at the surface. Lower surface tension allows water to spread more easily and penetrate fabrics and surfaces better, which is one reason why washing soda enhances cleaning effectiveness.

42. How does washing soda compare to potassium carbonate in terms of properties and uses?

Washing soda (sodium carbonate) and potassium carbonate have similar chemical properties as they are both alkali metal carbonates. However, potassium carbonate is more soluble in water and more hygroscopic (attracts moisture from the air). Washing soda is generally less expensive and more widely used in large-scale applications, while potassium carbonate finds specialized uses in certain industries like winemaking and some types of glass production.

43. How does washing soda affect the boiling point of water?

Washing soda, when dissolved in water, increases the boiling point of the solution. This is due to the colligative properties of solutions, specifically boiling point elevation. The dissolved ions of washing soda interfere with the escape of water molecules into the vapor phase, requiring more energy (higher temperature) for boiling to occur. This property is important in industrial processes and can affect cooking times in high-altitude locations.

44. How does washing soda contribute to the production of synthetic detergents?

Washing soda plays a role in the production of synthetic detergents as a source of alkalinity and as a builder. It helps to maintain an alkaline pH in detergent formulations, which enhances cleaning power. As a builder, it softens water by removing calcium and magnesium ions, improving the effectiveness of surfactants. In some processes, it's also used in the production of certain detergent raw materials.

45. What is the relationship between washing soda and the concept of Le Chatelier's principle?

Le Chatelier's principle can be applied to understand the behavior of washing soda in solution. For example, adding washing soda to water creates an equilibrium between carbonate, bicarbonate, and hydroxide ions. If an acid is added, the system will shift to counteract this change, consuming hydroxide ions and producing more bicarbonate. This principle explains why washing soda can act as a buffer in certain pH ranges.

46. What role does washing soda play in the production of certain dyes?

In dye production, washing soda can serve multiple purposes. It's used as an alkali in some dyeing processes to help fix dyes to fabrics. In the production of certain azo dyes, it can act as a buffering agent to control pH during reactions. Additionally, its alkaline nature can help in the extraction or purification of some natural dyes.

47. How does the thermal decomposition of washing soda occur, and what are its products?

When heated strongly, washing soda undergoes thermal decomposition. The reaction can be represented as: Na2CO3 → Na2O + CO2. This decomposition produces sodium oxide (Na2O) and carbon dioxide gas (CO2). The temperature at which this occurs is quite high, around 851°C (1564°F). Understanding this decomposition is important in high-temperature industrial processes involving washing soda.

48. How does washing soda interact with organic compounds, particularly in cleaning applications?

Washing soda interacts with organic compounds in several ways relevant to cleaning. Its alkaline nature can saponify fats and oils, turning them into water-soluble soap. It can also break down some protein-based stains. The high pH created by washing soda can denature proteins and disrupt the cell membranes of microorganisms, contributing to its cleaning and mild disinfectant properties.

49. What is the role of washing soda in the production of certain types of ceramics?

In ceramics production, washing soda can serve as a flux, lowering the melting point of other materials in the ceramic mixture. It can help create glazes with specific properties and can influence the color of certain ceramic products. Washing soda can also be used to adjust the pH of clay slips, affecting their rheological properties, which is important in casting processes.

50. How does washing soda compare to caustic soda (sodium hydroxide) in terms of alkalinity and applications?

While both are alkaline, caustic soda (NaOH) is a much stronger base than washing soda (Na2CO3). Caustic soda has a pH of about 14 in solution, while washing soda typically produces a pH around 11-11.5. Caustic soda is more corrosive and reactive, used in more aggressive cleaning and industrial processes. Washing soda is milder, making it more suitable for household cleaning and applications where a less aggressive alkali is needed.

51. What is the importance of washing soda in the context of buffer solutions?

Washing soda, when combined with sodium bicarbonate