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Baking Soda Washing Soda Plaster of Paris - Preparation, Formula, Uses, FAQs

Baking Soda Washing Soda Plaster of Paris - Preparation, Formula, Uses, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:26 PM IST

Sodium bicarbonate commonly called baking soda is the chemical compound formula NaHCO3. Sodium carbonate break down into sodium cation as well as a bicarbonate anion. Sodium carbonate can be obtained by heating baking soda, and recrystallization of sodium carbonate gives washing soda. It is also called basic salt.

This Story also Contains
  1. The preparation of Baking Soda:
  2. Washing Soda: What is washing soda/What is the formula of washing soda/What is the chemical formula of washing soda
  3. Washing Soda preparation:
  4. Uses of Washing Soda class 10
  5. Plaster of Paris
  6. How to prepare Plaster of Paris:
Baking Soda Washing Soda Plaster of Paris - Preparation, Formula, Uses, FAQs
Baking Soda Washing Soda Plaster of Paris - Preparation, Formula, Uses, FAQs

Baking Soda

The preparation of Baking Soda:

Baking soda is synthesized through Solvay’s process. Solvay’s process involves the reaction of Sodium Chloride, ammonia as well as carbon dioxide in water. The carbon dioxide involved is produced through Calcium Carbonate and the calcium oxide left is used in recovering ammonia from ammonium chloride. Finally, sodium bicarbonate is produced as one of the end products.

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Uses of Baking Soda

  • It is used as an ingredient in the manufacturing of antacids

  • It is used in making soft and fluffy bread and cakes due to the production of carbon dioxide when it is heated or mixed in water.

  • It is used for making soda-acid fire extinguishers.

Washing Soda: What is washing soda/What is the formula of washing soda/What is the chemical formula of washing soda

The powder in Washing Soda is whitish and odourless. Its chemical Washing Soda formula or washing powder formula is Na2CO3 and it is commonly called sodium carbonate. This substance is hygroscopic, which means that it absorbs moisture from the air. Water forms a strongly Alkaline solution at low concentrations, which is soluble in water. Washing Soda's chemical name is sodium carbonate and the chemical formula of washing soda/chemical formula of Washing Soda is Na2CO3.

Solvay synthesizes Washing Soda through a process that depends on phosphoric acid. Salovey’s process uses sodium chloride, ammonia, and carbon dioxide as catalysts.

Calcium carbonate generates carbon dioxide, and the leftover calcium oxide is used to recover ammonia from ammonium chloride. A sodium bicarbonate solution is first obtained, which is then converted to sodium carbonate by heating. Lastly, Washing Soda is produced by recrystallizing sodium carbonate.

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Washing Soda preparation:

The first step is to produce sodium bicarbonate, which is then converted to sodium carbonate. Last but not least, Washing Soda is made from sodium carbonate recrystallize.

The Solvay manufacturing process is used to make washing soda. It is manufactured via a reaction between sodium chloride, ammonia, and carbon dioxide in water. In this process, carbon dioxide is formed by manufacturing calcium carbonate and the calcium oxide left after is used to recover ammonia from ammonium chloride.

NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl

2 NaHCO3 → Na2CO3 + H2O + CO2

Na2CO3 + 10H2O → Na2CO3.10H2O

Uses of Washing Soda class 10

A common use of Baking Soda is to remove burnt-on grease from kitchen utensils. Several industries use this product, such as soap, glass, and paper.

This helps to remove the permanent hardness of the water. It is used for manufacturing various sodium compounds, for example, borax.

Plaster of Paris

This finely powdered chemical compound hardens when exposed to moisture and allowed to dry. It has the chemical formula CaSO4.1/2H2O and is sometimes referred to as Calcium Sulphate hemihydrate.

Plaster of Paris is a fine white powder consisting of a chemical compound that hardens after exposure to moisture in the air. It has the chemical formula CaSO4.1/2H2O and is sometimes referred to as calcium sulphate hemihydrate. In the manufacturing process, gypsum (CaSO4.2H2O) is used to make Plaster of Paris.

Gypsum becomes calcium sulphate (Plaster of Paris) after it is heated to 373 K, destroying its water molecules.

CaSO4.2H2O → CaSO4.1/2H2O + 3/2H2O

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How to prepare Plaster of Paris:

Gypsum (CaSO4.2H2O) is the basis of the Plaster of Paris. During heating at 373 K, gypsum loses its water molecules and forms calcium sulphate (Plaster of Paris).

CaSO4.2H2O → CaSO4.1/2H2O + 3/2H2O

Uses of Plaster of Paris

During fracture surgeries, doctors use Plaster of Paris to support fractured bones in the right position. It is used to produce toys and decorations. The surface smoothness of surfaces is also improved by it.


Frequently Asked Questions (FAQs)

1. How Can Baking Soda Be Used for Something So Surprising?

It is more effective than using distilled water or bleach alone for removing 80 percent of some pesticides from apples when soaked in Baking Soda and water for 12 to 15 minutes. 

The acids in Baking Soda assist with the breakdown of certain pesticides so they can be washed away. 

An effective, non-abrasive cleaner made with Baking Soda and water can be made at home. You can use it to wipe down the inside of a refrigerator of old food residue. Put Baking Soda on a carpet and let it sit for a while. Vacuum it up and your carpet won't stink anymore.

2. Baking Soda is also referred to as _______.

Sodium bicarbonate.

3. Identify the chemical formula of plaster in Paris?

CaSO4.1/2H2O

4. What are the common uses of sodium bicarbonate?

Sodium bicarbonate has a wide range of uses, including as a leavening agent in baking, a pH balancer in cooking and cleaning products, a cleaning agent for household surfaces, a deodorizer, and a medical treatment for conditions such as indigestion and acid reflux.

5. Can sodium bicarbonate be used as a substitute for baking powder?

Yes, sodium bicarbonate can be used as a substitute for baking powder in some recipes. To do this, you will need to combine sodium bicarbonate with an acid, such as cream of tartar or lemon juice, and a liquid, such as water or milk. This will create a chemical reaction that releases carbon dioxide gas, causing the dough or batter to rise.

6. How should sodium bicarbonate be stored?

Sodium bicarbonate should be stored in a cool, dry place away from heat and moisture. It is important to keep it in a tightly sealed container to prevent it from absorbing moisture from the air, which can cause it to lose its effectiveness.

7. What is Plaster of Paris, and how is it prepared?
Plaster of Paris is calcium sulfate hemihydrate (CaSO₄·½H₂O). It's prepared by heating gypsum (CaSO₄·2H₂O) to about 120°C, causing it to lose water molecules. The reaction is: CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂O
8. Why does Plaster of Paris harden when mixed with water?
When water is added to Plaster of Paris, it rehydrates and forms gypsum again. This process is called setting. The plaster absorbs water and interlocking crystals of gypsum form, causing the mixture to harden. The reaction is: CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O
9. Why is Plaster of Paris stored in airtight containers?
Plaster of Paris is stored in airtight containers to prevent it from absorbing moisture from the air. If exposed to humidity, it can slowly rehydrate and form gypsum, which would render it ineffective for its intended use. Keeping it dry preserves its ability to set when intentionally mixed with water.
10. How does the crystal structure of Plaster of Paris change when it sets?
When Plaster of Paris sets, its crystal structure changes from calcium sulfate hemihydrate (CaSO₄·½H₂O) to calcium sulfate dihydrate (CaSO₄·2H₂O), also known as gypsum. This involves the incorporation of water molecules into the crystal lattice, forming a more stable and rigid structure.
11. Why is Plaster of Paris used in making casts for broken bones?
Plaster of Paris is used for making casts because it can be easily molded when mixed with water and then hardens quickly. As it sets, it generates only a small amount of heat, making it safe for use on the skin. The resulting cast is lightweight, porous (allowing skin to breathe), and provides good support for healing bones.
12. Why is Plaster of Paris sometimes called calcined gypsum?
Plaster of Paris is called calcined gypsum because it's produced by calcining (heating) gypsum. The process of heating gypsum (CaSO₄·2H₂O) drives off some of the water of crystallization, resulting in calcium sulfate hemihydrate (CaSO₄·½H₂O), which is Plaster of Paris.
13. How does the presence of impurities affect the setting time of Plaster of Paris?
Impurities can significantly affect the setting time of Plaster of Paris. Some impurities, like alum or potassium sulfate, can act as accelerators, reducing setting time. Others, like borax or organic compounds, can act as retarders, increasing setting time. The type and amount of impurities present can thus be used to control the setting properties.
14. How does the solubility of Plaster of Paris change with temperature?
The solubility of Plaster of Paris (calcium sulfate hemihydrate) generally decreases as temperature increases, which is opposite to the behavior of many other salts. This unusual property is due to the exothermic nature of its dissolution process. However, the relationship is not linear and can be complex at certain temperature ranges.
15. How does the reaction of Plaster of Paris with water demonstrate Le Chatelier's principle?
The setting of Plaster of Paris demonstrates Le Chatelier's principle. When water is added to calcium sulfate hemihydrate (CaSO₄·½H₂O), it shifts the equilibrium towards the formation of calcium sulfate dihydrate (CaSO₄·2H₂O). This shift occurs to counteract the increase in water concentration, following Le Chatelier's principle.
16. What is the chemical formula of baking soda?
The chemical formula of baking soda is NaHCO₃. It is also known as sodium bicarbonate or sodium hydrogen carbonate.
17. What is the chemical reaction that occurs when baking soda is heated?
When baking soda (NaHCO₃) is heated, it decomposes to form sodium carbonate (Na₂CO₃), water vapor (H₂O), and carbon dioxide (CO₂). The reaction is: 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂
18. Why does baking soda cause baked goods to rise?
Baking soda causes baked goods to rise because it reacts with acidic ingredients in the batter (like vinegar, lemon juice, or buttermilk) to produce carbon dioxide gas. This gas forms bubbles in the batter, which expand during baking, causing the dough or batter to rise and become light and fluffy.
19. Why is baking soda considered an amphoteric substance?
Baking soda (NaHCO₃) is amphoteric because it can act as both an acid and a base. In the presence of a strong acid, it acts as a base and accepts protons. In the presence of a strong base, it acts as an acid and donates protons.
20. What role does baking soda play in fire extinguishers?
Baking soda is used in some fire extinguishers because when heated, it decomposes to produce carbon dioxide. This CO₂ helps smother the fire by displacing oxygen. Additionally, the decomposition is endothermic, absorbing heat from the fire.
21. How does the structure of washing soda contribute to its water-softening properties?
Washing soda (Na₂CO₃) is effective at softening water because its carbonate ions (CO₃²⁻) can precipitate calcium and magnesium ions, which cause water hardness. The sodium ions replace these hard water ions, effectively softening the water.
22. Why is washing soda used in the manufacture of glass?
Washing soda (Na₂CO₃) is used in glass manufacturing because it lowers the melting point of silica (SiO₂), the main component of glass. This makes the glass-making process more energy-efficient. The sodium ions from washing soda also become part of the glass structure, affecting its properties.
23. What is the environmental impact of using washing soda as a cleaning agent?
Washing soda (Na₂CO₃) is generally considered environmentally friendly. It's biodegradable and doesn't contain phosphates or other harmful chemicals. However, its high alkalinity can be harmful to aquatic life if released in large quantities. It's important to use it responsibly and dispose of it properly.
24. How does the solubility of baking soda compare to that of washing soda?
Washing soda (Na₂CO₃) is generally more soluble in water than baking soda (NaHCO₃). At room temperature, the solubility of washing soda is about 30g/100mL, while baking soda's solubility is about 9g/100mL. This difference is due to their different molecular structures and ion interactions.
25. Why is baking soda effective as a deodorizer?
Baking soda is effective as a deodorizer because it can neutralize both acidic and basic odor molecules. Its amphoteric nature allows it to react with a wide range of odor-causing chemicals, converting them into neutral, odorless salts. Additionally, its porous structure can absorb odors.
26. What is the role of washing soda in the Solvay process?
In the Solvay process, washing soda (Na₂CO₃) is the final product. The process uses ammonia, carbon dioxide, and sodium chloride to produce sodium bicarbonate, which is then heated to form washing soda. This industrial process is a major method for producing sodium carbonate on a large scale.
27. How does the thermal stability of baking soda compare to that of washing soda?
Baking soda (NaHCO₃) is less thermally stable than washing soda (Na₂CO₃). When heated, baking soda decomposes into washing soda, water, and carbon dioxide at around 50°C. Washing soda, on the other hand, remains stable at much higher temperatures, only decomposing at over 850°C.
28. How does the pH of a solution change when equal amounts of baking soda and washing soda are added?
When equal amounts of baking soda (NaHCO₃) and washing soda (Na₂CO₃) are added to a solution, the pH will increase more with washing soda. This is because washing soda is a stronger base and dissociates more completely in water, releasing more hydroxide ions (OH⁻) which increase the pH more significantly.
29. What is the difference between anhydrous sodium carbonate and washing soda?
Anhydrous sodium carbonate (Na₂CO₃) and washing soda (Na₂CO₃·10H₂O) have the same chemical formula for the carbonate part, but washing soda is the decahydrate form, containing 10 water molecules per formula unit. Anhydrous sodium carbonate is a white powder, while washing soda forms colorless crystals.
30. How does the reaction of washing soda with calcium ions in water treatment differ from that of baking soda?
Washing soda (Na₂CO₃) reacts more strongly with calcium ions in water compared to baking soda (NaHCO₃). Washing soda forms insoluble calcium carbonate precipitate: Na₂CO₃ + Ca²⁺ → CaCO₃↓ + 2Na⁺. Baking soda can also react, but less effectively: 2NaHCO₃ + Ca²⁺ → Ca(HCO₃)₂ + 2Na⁺. The calcium bicarbonate formed is more soluble than calcium carbonate.
31. How is washing soda different from baking soda?
Washing soda (Na₂CO₃) is sodium carbonate, while baking soda (NaHCO₃) is sodium bicarbonate. Washing soda has a higher pH and is more alkaline than baking soda. It's also more caustic and used for heavy-duty cleaning, while baking soda is milder and used in cooking and light cleaning.
32. How does the pH of a baking soda solution compare to that of a washing soda solution?
A washing soda (Na₂CO₃) solution has a higher pH than a baking soda (NaHCO₃) solution. Washing soda is more alkaline, typically with a pH around 11-12, while baking soda has a pH of about 8-9. This is because washing soda is a stronger base.
33. How does the addition of baking soda affect the pH of an acidic solution?
Adding baking soda to an acidic solution increases its pH, making it less acidic. Baking soda (NaHCO₃) reacts with hydrogen ions (H⁺) from the acid, neutralizing them and producing water and carbon dioxide. This buffering action helps to raise the pH towards neutral.
34. What is the significance of the "bi" in sodium bicarbonate?
The "bi" in sodium bicarbonate indicates that it contains one hydrogen atom that can be replaced by a metal. It signifies that it's an acid salt, containing both a replaceable hydrogen atom and a metal (sodium in this case). This is why it's also called sodium hydrogen carbonate.
35. How does the reaction of baking soda with vinegar demonstrate acid-base chemistry?
When baking soda (NaHCO₃) reacts with vinegar (CH₃COOH), it demonstrates acid-base chemistry. The reaction produces sodium acetate, water, and carbon dioxide: NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂. This reaction shows how an acid and a base neutralize each other, producing a salt and water, along with CO₂ gas.
36. How does the presence of baking soda in a refrigerator help keep it odor-free?
Baking soda in a refrigerator absorbs odors due to its porous structure and its ability to neutralize both acidic and basic odor molecules. It doesn't just mask smells but chemically changes odor-causing compounds into neutral, odorless salts. This process is continuous, making it effective over time.
37. How does the addition of baking soda affect the browning of foods during cooking?
Adding baking soda to foods can promote browning during cooking. It raises the pH, which accelerates the Maillard reaction - a chemical reaction between amino acids and reducing sugars that gives browned foods their distinctive flavor. This is why it's sometimes added to cookies or pretzels to enhance browning.
38. Why is baking soda sometimes used in swimming pools?
Baking soda is used in swimming pools as a pH buffer. It helps maintain a stable pH level, preventing rapid changes that could be harmful to swimmers or damage pool equipment. It also increases the total alkalinity of the water, which helps resist changes in pH caused by acidic contaminants.
39. How does the crystal structure of washing soda contribute to its water-absorbing properties?
Washing soda (Na₂CO₃·10H₂O) has a crystal structure that includes water molecules. This hydrated form can easily lose some of its water molecules when exposed to dry air, and reabsorb them in humid conditions. This property makes it an effective desiccant (drying agent) in certain applications.
40. What is the role of baking soda in antacid medications?
Baking soda is used in some antacid medications due to its ability to neutralize stomach acid. When it reacts with hydrochloric acid in the stomach, it forms sodium chloride, water, and carbon dioxide: NaHCO₃ + HCl → NaCl + H₂O + CO₂. This reaction increases the pH in the stomach, providing relief from acid reflux and heartburn.
41. Why is washing soda more effective than baking soda for removing grease stains?
Washing soda (Na₂CO₃) is more effective than baking soda (NaHCO₃) for removing grease stains because it's a stronger base. Its higher pH allows it to better break down and emulsify fats and oils. Additionally, its higher alkalinity can saponify fats, turning them into soap, which further aids in cleaning.
42. How does the presence of baking soda affect the leavening process in baked goods compared to yeast?
Baking soda provides chemical leavening, while yeast provides biological leavening. Baking soda reacts quickly with acidic ingredients to produce carbon dioxide gas, causing immediate rise. Yeast, on the other hand, produces CO₂ through fermentation, a slower process that also contributes to flavor development. Baking soda is used for quick breads, while yeast is used for products that require longer rising times.
43. What is the significance of the water of crystallization in washing soda?
The water of crystallization in washing soda (Na₂CO₃·10H₂O) is significant for several reasons. It affects the crystal structure, solubility, and melting point of the compound. The presence of water molecules also makes washing soda effective as a desiccant. When heated, washing soda can lose this water, forming anhydrous sodium carbonate.
44. Why is baking soda sometimes added to swimming pools in addition to chlorine?
Baking soda is added to swimming pools to increase total alkalinity and help stabilize pH. While chlorine disinfects the water, it can also lower pH. Baking soda acts as a buffer, preventing rapid pH changes that could irritate swimmers' skin and eyes or damage pool equipment. It helps maintain the effectiveness of chlorine by keeping the pH in the optimal range.
45. How does the thermal decomposition of washing soda differ from that of baking soda?
The thermal decomposition of washing soda (Na₂CO₃) occurs at a much higher temperature than baking soda (NaHCO₃). Baking soda decomposes around 50°C to form washing soda, water, and carbon dioxide. Washing soda, however, is stable up to about 850°C, at which point it begins to decompose into sodium oxide (Na₂O) and carbon dioxide (CO₂).

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