What is the Difference Between Aluminum Sulfate and Ammonium Sulfate

Inorganic compounds are substances that do not contain carbon-hydrogen bonds. They can be made up of elements from the periodic table, such as metals, nonmetals, and metalloids. Aluminum sulfate and ammonium sulfate are two such inorganic compounds.

What is the difference between aluminum sulfate and ammonium sulfate? Aluminum sulfate contains aluminum and sulfate ions, whereas ammonium sulfate contains sulfate ions and ammonium ions.

Key Areas Covered

1. What is Aluminum Sulfate  
      – Definition, Features 
2. What is Ammonium Sulfate
      – Definition, Features 
3. Similarities Between Aluminum Sulfate and Ammonium Sulfate
      – Outline of Common Features
4. Difference Between Aluminum Sulfate and Ammonium Sulfate 
      – Comparison of Key Differences
5. FAQ: Aluminum Sulfate and Ammonium Sulfate
      – Answers to Frequently Asked Questions

Key Terms

Aluminum Sulfate, Ammonium Sulfate

Difference Between Aluminum Sulfate and Ammonium Sulfate - Comparison Summary

What is Aluminum Sulfate

Aluminum sulfate is called alum. It is a compound with the chemical formula Al₂(SO₄)₃. It is a white crystalline solid that is highly soluble in water.  The compound is made up of two types of ions: aluminum and sulfate ions. It consists of two aluminum ions coordinating with three sulfate ions.

Aluminum sulfate is formed by the reaction of aluminum hydroxide (Al(OH)₃) with sulfuric acid (H₂SO₄):

2Al(OH)₃ + 3H₂SO₄ → Al₂(SO₄)₃ + 6H₂O

It decomposes upon heating. Another special feature of it is its hygroscopic nature (hygroscopic – absorbs moisture from the air).

Aluminum Sulfate

This compound participates in various different chemical reactions to form other compounds. For example, in aqueous solutions, aluminum sulfate undergoes hydrolysis to produce aluminum hydroxide and sulfuric acid.

Al₂(SO₄)₃ + 6H₂O → 2Al(OH)₃ + 3H₂SO₄

Aluminum sulfate can form complexes with various ligands, such as fluoride ions (F⁻) and oxalate ions (C₂O₄²⁻).

Aluminum has a large number of applications. In water treatment, it is used as a coagulant to get rid of impurities. In the paper-making industry, it is used as a sizing agent to improve paper quality. Moreover, in the textile industry, it is used as a mordant to fix dyes to fabrics. It is used as a clarifying agent in the food processing industry. Additionally, in the pharmaceutical industry, it is used as an excipient in certain medications.

What is Ammonium Sulfate

Ammonium sulfate is a chemical compound with the formula (NH₄)₂SO₄. It is a white crystalline solid with a higher solubility in water. Ammonium compound is a salt consisting of ammonium and sulfate ions. Its structure is a crystalline solid, held together by ionic bonds between these ions.

Ammonium Sulfate

Ammonium sulfate is formed by the neutralization reaction between sulfuric acid (H₂SO₄) and ammonia.

(NH₃): H₂SO₄ + 2NH₃ → (NH₄)₂SO₄

Ammonium sulfate is a relatively stable compound and does not readily react with most other substances. However, it can react with strong bases to produce ammonia and the corresponding sulfate salt.

In agriculture, ammonium sulfate is useful as a fertilizer because of its high amount of nitrogen content. Moreover, ammonium sulfate acidifies the soil. It is used in water treatment and is used as a coagulant that removes impurities.

Similarities Between Aluminum Sulfate and Ammonium Sulfate

  1. These compounds contain the sulfate ion (SO₄²⁻) as a common component.
  2. Both compounds are highly soluble in water.
  3. Moreover, both are inorganic compounds.
  4. They are used in agriculture.
  5. Additionally, both are ionic compounds.

Difference Between Aluminum Sulfate and Ammonium Sulfate

Definition

  • Aluminum sulfate has the chemical formula Al₂(SO₄)₃, containing aluminum cations (Al³⁺) and sulfate anions (SO₄²⁻). Ammonium sulfate, on the other hand, has the chemical formula (NH₄)₂SO₄, containing ammonium cations (NH₄⁺) and sulfate anions (SO₄²⁻).

Cations

  • Aluminum sulfate contains aluminum cations while ammonium sulfate contains ammonium cations.

Use

  • Aluminum sulfate is primarily used as a coagulant in water treatment, while ammonium sulfate is commonly used as a fertilizer.

Conclusion

Aluminum sulfate and ammonium sulfate are two chemically different inorganic ionic compounds that have applications across various industries. Moreover, the main difference between aluminum sulfate and ammonium lies in their chemical composition. Aluminum sulfate contains aluminum and sulfate ions, whereas ammonium sulfate contains sulfate ions and ammonium ions.

FAQ: Aluminum Sulfate and Ammonium Sulfate

1. What does aluminium sulphate do to soil?

Aluminium sulphate lowers soil pH, making it more acidic. This can be beneficial for acid-loving plants but harmful to others. It can also help to improve soil structure and drainage.

2. What are the disadvantages of aluminium sulphate?

Aluminium sulphate has several disadvantages. It can contribute to acid rain and harm aquatic life. Moreover, exposure to aluminium sulphate can cause skin irritation and respiratory problems. It can corrode metals and materials, leading to damage.

3. What plants benefit from aluminum sulfate?

Aluminum sulfate is used to acidify soil for plants that prefer acidic conditions, such as azaleas, rhododendrons, and blueberries.

4. What happens when aluminium sulphate reacts with water?

Aluminium sulphate reacts with water to form hydrated aluminium sulphate. The hydrated aluminium sulphate is a crystalline solid with a blue-green color. The reaction is exothermic, meaning that it releases heat.

5. Can aluminium sulphate be used in water treatment?

Yes, aluminum sulfate can be used in water treatment. It acts as a coagulant, causing suspended particles to clump together and settle, making the water clearer.

Reference:

1. “Aluminum Sulfate.” Science Direct.
2. “Ammonium Sulfate.” Science Direct.

Image Courtesy:

1. “Aluminium Sulfate” By Picture taken by Martin Walker in June 2005. (Public Domain) via Commons Wikimedia
2. “Ammonium Sulfate” By Edgar181 – Own work (Public Domain) via Commons Wikimedia 

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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