Preparation of Potash Alum – Formula, Uses, Procedure and Viva Voice

Preparation of Potash Alum

Potash alum is a potassium aluminum sulfate dodecahydrate. It is a white solid that is soluble in water. It is used as a flocculant in water treatment and as a coagulant in the production of paper. In this blog, let us delve into what potash alum is, its properties, the preparation of Potash Alum and other related information.

To prepare potash alum, potassium sulfate and aluminum sulfate are mixed in the appropriate proportions. The mixture is then heated to a high temperature to produce potash alum.

What is the Formula of Potash Alum?

The formula of potash alum is KAl(SO4)2·12H2O.

Uses of Potash Alum

Potash alum, also known as potassium aluminum sulfate, has a variety of practical uses due to its properties. Some common uses of potash alum include:

1. Food Preservation: Potash alum is used as a food preservative, especially in pickling. Its antimicrobial properties help prevent the growth of spoilage-causing microorganisms.
2. Water Purification: Potash alum is added to water to clarify it by causing impurities and suspended particles to settle down. This process is known as flocculation and is often used in water treatment plants.
3. Leather Tanning: It is used in the process of tanning leather to help stabilize the structure of the leather fibers and make them more durable.
4. Fire Extinguisher: In some fire extinguishers, a solution of potash alum is used as a fire suppressant due to its ability to smother flames.
5. Cosmetics and Personal Care: Potash alum is used in various cosmetic and personal care products like aftershaves, deodorants, and antiperspirants due to its astringent and antibacterial properties.
6. Medicine: In traditional medicine, alum is sometimes used topically to stop bleeding from minor cuts and abrasions due to its ability to constrict blood vessels.
7. Paper Industry: It’s used in the paper industry as a sizing agent to improve the paper’s resistance to ink penetration and improve its writing quality.
8. Textile Industry: In textiles, potash alum can be used as a mordant to enhance the dye absorption by the fibers.
9. Baking Powder: Potash alum was used historically as a leavening agent in baking before modern baking powder was developed.
10. Art and Crafts: Alum is used in various artistic processes, such as in certain dyeing techniques and marbling of paper.
11. Skin Tightening: Some traditional beauty practices involve using alum to tighten the skin, but its use in this context can be irritating to the skin and is not recommended.
12. Crystal Growth: Alum crystals are often used in educational settings to demonstrate the process of crystal growth.

Also read: Preparation of Inorganic Compounds

Preparation of Potash Alum

• Potash alum is a potassium aluminum sulfate dodecahydrate. It is a white crystalline solid that is soluble in water. It is used in the manufacture of paper, dyes, and fireworks.
• The first step in the preparation of potash alum is the preparation of aluminum sulfate. Aluminum sulfate is made by reacting aluminum metal with sulfuric acid.
• The second step is the preparation of potassium sulfate. Potassium sulfate is made by reacting potassium hydroxide with sulfuric acid.
• The third step is the reaction of aluminum sulfate and potassium sulfate to form potash alum. Potash alum is made by reacting aluminum sulfate and potassium sulfate in the presence of a sulfuric acid catalyst.

Procedure for Preparation of Potash Alum

• Potash alum is commercially available. It can also be prepared in the laboratory by the reaction of potassium sulfate and aluminum sulfate.
• The reactants are dissolved in water and the solution is heated to boiling.
• The solution is then allowed to cool and the alum crystals are collected by filtration.

Equation 1: Preparation of Potash Alum

Potassium aluminum sulfate, KAl(SO4)2, is a white solid that is soluble in water. It is used in the manufacture of paper and as a flocculant in water treatment.

In this experiment, you will prepare a sample of potash alum by reacting potassium sulfate and aluminum sulfate.

Equipment

1. 10% sulfuric acid
2. 3 beakers
3. 100 mL graduated cylinder
4. Teaspoon
5. Watch glass

Procedure

1. Measure out 10 mL of 10% sulfuric acid into a beaker.
2. Add 1 teaspoon of potassium sulfate to the beaker of sulfuric acid.
3. Stir the solution until the potassium sulfate is dissolved.
4. Add 1 teaspoon of aluminum sulfate to the beaker of sulfuric acid.
5. Stir the solution until the aluminum sulfate is dissolved.
6. Place a watch glass over the beaker and allow the solution to cool.
7. When the solution has cooled, place the beaker in the refrigerator overnight.
8. The next day, remove the beaker from the refrigerator and filter the solution through a coffee filter.
9. Discard the coffee filter and return the potash alum to the refrigerator.

Equation 2: Calculation of Percentage Yield

Percentage yield = Actual yield/Theoretical yield × 100%

= (9.5 g/10 g) × 100%
= 95%

Equation 3: Number of Moles of Oxygen

The number of moles of oxygen is found by multiplying the number of atoms of oxygen by the Avogadro constant.

There are six atoms of oxygen in one mole.

6 moles of oxygen

The Theory of Potash Alum

• Potash alum is potassium aluminum sulfate dodecahydrate. It is a white crystalline solid that is soluble in water. It is used as a flocculant in water treatment and in the production of paper.
• The potassium aluminum sulfate in potash alum is a Lewis acid. The sulfate ion is a Lewis base. When the two ions come together, they form an alum salt. This salt crystallizes out of the solution and can be collected.

Frequently Asked Questions (FAQs) on Potash Alum

What is Potash Alum Used For?

Potash alum, or potassium aluminum sulfate, has versatile applications. It's used in water purification, food preservation, leather tanning, fire extinguishers, cosmetics, and more.

Is Potash Alum Safe for Skin?

Potash alum is used in some cosmetic products, but direct application to skin can cause irritation. It's important to use alum-containing products cautiously and follow guidelines.

Can I Use Potash Alum for Water Purification at Home?

Yes, potash alum can be used for water clarification at home. However, proper dosing and understanding the process are crucial. It's recommended to consult experts for safe usage.

What Are the Health Concerns with Potash Alum?

While potash alum has many industrial and traditional uses, excessive consumption or improper use can have health risks. Always follow recommended guidelines and consult professionals.

Is Potash Alum the Same as Baking Powder?

No, potash alum is not the same as baking powder. It was used historically for leavening, but modern baking powder is a safer and more effective alternative for baking.

Is Potash Alum Eco-friendly?

Potash alum can have environmental impacts, especially when used in large quantities. It's advisable to consider alternative eco-friendly options for various applications.

Is Potash Alum the Same as Regular Alum?

Potash alum and regular alum are both types of aluminum sulfate compounds with distinct properties. Potash alum is often potassium aluminum sulfate, while regular alum can refer to aluminum sulfate or other variations.