Plaster of Paris, Baking Soda and Washing Soda

Plaster of Paris, Baking Soda and Washing Soda are a few compounds which are widely used in our daily life. Sodium bicarbonate commonly known as baking soda is a chemical compound with the formula NaHCO₃. Sodium carbonate commonly known as washing soda is a chemical compound with the formula Na₂CO₃. Calcium Sulphate Hemihydrate commonly known as Plaster of Paris is a chemical compound with the formula CaSO₄.1/2H₂O.

In this article, we will learn about Plaster of Paris, Baking Soda and Washing Soda, its preparation, properties, and uses in detail.

Plaster of Paris

Plaster of Paris is a quick-setting gypsum plaster made of fine white powder (calcium sulphate hemihydrate) that hardens when wet and left to dry. Plaster of Paris, known since ancient times, is so named due to its production from the plentiful gypsum found in Paris.

When dry, the plaster of Paris does not shrink or fracture, making it an excellent material for casting moulds. It is often used to create and hold decorative plasterwork on ceilings and cornices. It’s also used in medicine to produce plaster casts to keep broken bones immobilized while they recover, however many current orthopaedic casts are composed of fibreglass or thermoplastics.

Plaster of Paris Formula

Plaster of Paris is also known as Calcium Sulphate Hemihydrate. The chemical formula of Plaster of Paris is CaSO₄.1/2H₂O.

Preparation of Plaster of Paris

Plaster of Paris is (POP) prepared from the chemical compound, calcium sulfate dihydrate, which is also known as, gypsum. Gypsum is represented by the chemical formula CaSO₄.2H₂O. POP is manufactured by heating the element gypsum at a very high temperature of about 373 K. When this happens at such a high-temperature value of 373 K, approximately three-fourths of its water of crystallization is lost, forming POP.

CaSO₄ · 2H₂O + Heat ⇢ CaSO4 · 1/2 H₂O + 3/2 H₂O (Discharged as steam)

Since the presence of moisture may slow down the setting of plaster by bringing about the hydration process. Therefore, it is stored in moisture-proof containers.

Properties of Plaster of Paris

Plaster of Paris exhibits the following properties,

• Plaster of Paris is a white-coloured powder, that forms crystals of gypsum when mixed with water.
• It forms an anhydrous calcium sulphate on heating at 473 K. 
• It expands slowly and slightly upon setting.
• It does not cause cracking of surfaces.
• It gives a decorative interior finish.

Uses of Plaster of Paris

Plaster of Paris founds its usage in the following areas,

• 3D Printing: Gypsum plaster can be used for 3D Printing. The water is applied by the inkjet head.
• Architecture and Decorations: Plaster of Paris is used to produce fine artwork to decorate and beautify monuments and buildings. It is also used to imitate wood or stone which is found in ancient buildings and monuments.
• During Burial Services: Plaster of Paris is used by executives of funeral houses in order to remake the damaged tissues and fill up the wounds.
• Medicines: It is used as a mould and cast. It is used to heal broken bones and cast into a supportive coating known as an orthopaedic cast.
• Fireproofing and fire protection systems.

Washing Soda (Sodium Carbonate)

Washing soda is used in a variety of applications, ranging from home to industrial. It’s an alkaline substance with a high alkaline character that can eliminate stubborn stains from textiles while they’re being washed. The formula for washing soda is Na₂CO₃.10H₂O. Sodium carbonate is the chemical term for washing soda. Soda ash is a hydrated salt of sodium carbonate in chemical terms.

Sodium Carbonate Formula

Sodium Carbonate is also known as Washing Soda. The chemical formula of Sodium Carbonate or Washing Soda is Na₂CO₃.10H₂O, where 10H₂O is the water of crystalization.

Preparation of Sodium Carbonate

Solvay method is required for the synthesis of sodium carbonate, and the steps involved in sodium carbonate manufacturing are described below:

Step 1: Purification of Brine

A solution of salt and water, called brine is purified in the first step. This process is important to remove the impurities and therefore increase the yield of the final product. Evaporation produces concentrated brine, while precipitation removes impurities such as calcium, magnesium, and other minerals coming from the rock salts. The concentrated brine solution is filtered before being mixed with ammonia in the ammonia tower.

Step 2: Formation of Sodium Hydrogen Carbonate

In the second step, purified brine is transferred into another chamber, and ammonia passes through it. This ammonia reacts with salt water to give ammoniated brine and heat. In the next step, this ammoniated brine reacts with Carbon dioxide (produced via decomposing CaCO₃ at 900°C) to give sodium bicarbonate and ammonium chloride. These conditions are controlled in such a way as to maximise the precipitation of sodium bicarbonate, which is extracted using a rotary pump.

NH₃ + CO₂ + NaCl + H₂O → NaHCO₃ + NH₄Cl

Step 3: Formation of Sodium Carbonate

In this step sodium carbonate (Na₂CO₃) is produced by the thermal decomposition of sodium bicarbonate (NaHCO₃) at 300°C. As a result, sodium carbonate crystals form.

2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

Step 4: Recovery of Ammonia

This process involves the recovery of ammonia from the previous steps. In this step, a distillation column is used to recover ammonia. First NH₄Cl solution is treated with lime water (Ca(OH)₂) to obtain the ammonia as the final product. The Solvay process uses this ammonia again, and CaCl₂ is obtained as a by-product.

2NH₄Cl + Ca(OH)₂ → 2NH₃ + CaCl₂ + H₂O

Properties of Sodium Carbonate

Various Properties of Sodium Carbonate are,

• It’s a crystalline solid that’s white in colour.
• It comes in monohydrated (Na₂CO₃.10H₂O), anhydrous (Na₂CO₃), heptahydrate (Na₂CO₃.7H₂O), and decahydrate (Na₂CO₃.10H₂O) forms.
• In nature, sodium carbonate is a basic substance.
• It has a melting point of 851°C.
• It loses its water in the presence of heat and forms an anhydrous salt (soda ash).

Na₂CO₃.10H₂O → Na₂CO₃.H₂O → Na₂CO₃ (at 373 K)

Uses of Sodium Carbonate

Various uses of Sodium Carbonate are discussed below in this article,

• In industry and the home, it is used as a cleaning agent.
• It’s used in the paper, textile, soap, and detergent sectors, among others.
• It is utilised in the water-softening process.
• It’s a material used in the production of glass.
• In laundries, it is one of the most significant agents.

Baking Soda (Sodium Bicarbonate)

Sodium bicarbonate is also known as Baking Soda. Baking soda’s chemical formula is NaHCO₃.

Sodium Bicarbonate is another name for baking soda. Natron, a natural deposit mostly composed of Na₂CO₃, was first quarried by the Medieval Egyptians. It was used as soap. Nicolas Leblanc, a French chemist, created NaHCO₃ for the first time in 1790. In 1846, John Dwight and Austin Church established a baking soda manufacturing plant employing sodium carbonate and carbon dioxide.

Various chemistry applications can be found in every room of the house, including the bathroom, kitchen, and so on. Sodium bicarbonate is one such substance, which is widely utilised due to its versatility, utility, and low cost.

Sodium Bicarbonate Formula

Sodium Bicarbonate is also known as Baking Soda. The chemical formula of Sodium Bicarbonate or Baking Soda is NaHCO₃.

Preparation of Sodium Bicarbonate: Solvay Process

Ernest Solvay, an Italian chemist developed this method in 1861 to produce sodium bicarbonate. The steps following the formation of sodium bicarbonate are given below,

Production of Sodium Hydrogen Carbonate

In the industrial world, the Solvay process is used to make sodium bicarbonate and sodium carbonate. Carbon dioxide, water, ammonia, and concentrated brine solution are employed as raw materials in this process. This method is preferred because it is less expensive and requires fewer raw resources to create the required chemicals. Baking soda and sodium carbonate are made through a chemical reaction that goes like this,

CO₂ + H₂O + NH₃ + NaCl → NaHCO₃ + NH₄Cl

2 NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

The carbon dioxide that is created is recycled to make NaHCO₃.

Properties of Sodium Bicarbonate

Various properties of Sodium Bicarbonate are,

• It is non-combustible.
• Powder dust isn’t as explosive as other types of dust.
• It has a melting point of 50°C.
• NaHCO₃ is a crystalline white substance with no odour.
• It is fundamental in nature.

Uses of Sodium Bicarbonate

Various uses of Sodium Bicarbonate are discussed below in this article,

• Reduces stomach acidity and acts as an antacid to relieve stomach discomfort and indigestion.
• As a water softener, it is used in the washing process.
• It is utilised in fire extinguishers because it produces soapy foam.
• Acts as a pesticide by removing dirt from materials without affecting their properties.
• Carbon dioxide is produced (due to the decomposition of NaHCO₃), which aids in the rising of dough in the baking industry.
• It’s found in ear drops, cosmetics, and other personal care items.
• It’s utilised to counteract the effects of acid by acting as a neutralizer.

Read, More

• Some Important Compounds of Sodium
• Some Important Compounds of Calcium
• Acids, Bases and Salts

Frequently Asked Questions

Question 1: What is the Chemical Formula of Baking Soda?

Answer:

The chemical formula of baking soda is NaHCO₃. It is also called as sodium bicarbonate.

Question 2: What is Baking Soda also known as?

Answer:

The chemical name of baking soda is Sodium bicarbonate.

Question 3: List Uses of Baking Soda.

Answer:

Various uses of Baking Soda are,

• Reduces stomach acidity and acts as an antacid to relieve stomach discomfort and indigestion.
• It is used as a water softener in the washing process.

Question 4: What is the Chemical Formula of the Plaster of Paris?

Answer:

The chemical formula of Plaster of Paris is CaSO₄.1/2H₂O

Question 5: What is Plaster of Paris also known as?

Answer:

The chemical name of Plaster of Paris is Calcium Sulphate hemihydrate.

Question 6: List uses of Plaster of Paris.

Answer:

Various uses of Plaster of Paris are,

• Plaster of Paris is used in coating walls and ceilings. 
• Plaster of Paris is used by doctors as a plaster for setting fractured bones.

Question 7: What is Washing Soda also known as?

Answer:

The chemical name of washing soda is Sodium carbonate.

Question 8: What is the Chemical Formula of Washing Soda?

Answer:

The chemical formula of washing soda is Na₂CO₃.

Question 9: List Uses of Washing Soda.

Answer:

Various uses of Washing soda are,

• In industry and the home, it is used as a cleaning agent.
• It’s used in the paper, textile, soap, and detergent sectors, among others.