Difference Between Sodium Hydroxide and Aluminum Hydroxide

Key difference - sodium hydroxide vs. aluminum hydroxide

Sodium hydroxide and aluminum hydroxide are metal hydroxides . The chemical formula of sodium hydroxide is NaOH . The common name for sodium hydroxide is caustic soda . It's an ionic compound . Aluminum hydroxide is an amphoteric hydroxide that has both acidic and basic properties. The chemical formula of aluminum hydroxide is Al (OH) 3 . The main difference between sodium hydroxide and aluminum hydroxide is that sodium hydroxide is a basic compound while aluminum hydroxide is an amphoteric compound.

Key areas covered

1. What is sodium hydroxide - definition, chemical properties, applications 2. What is aluminum hydroxide - definition, chemical properties, applications 3. What is the difference between sodium hydroxide and aluminum hydroxide - comparison of the main differences

Key terms: aluminum hydroxide (Al (OH) 3 ), amphoteric, Brønsted-Lowry base, caustic soda, exothermic, hygroscopic, Lewis acid, sodium hydroxide (NaOH)

Difference Between Sodium Hydroxide and Aluminum Hydroxide - Comparative Summary

What is Sodium Hydroxide?

Sodium hydroxide is a metal hydroxide with the chemical formula NaOH . The common name for sodium hydroxide is caustic soda . Sodium hydroxide is an ionic compound made up of sodium cations (Na + ) and hydroxide (OH - ) anions. It's a strong base .

The molar mass of sodium hydroxide is 39.99 g / mol. Sodium hydroxide is a solid at room temperature and appears as white, waxy crystals that are opaque. It's odorless. The melting point of sodium hydroxide is 318 ° C and the boiling point is 1,388 ° C.

Difference Between Sodium Hydroxide and Aluminum Hydroxide

Figure 1: Solid sodium hydroxide compound

Since sodium hydroxide is a very basic compound, it can cause severe burns. It is highly soluble in water. When dissolved in water, this ionic compound dissociates into its ions. This dissolution in water is strongly exothermic . Sodium hydroxide is hygroscopic . This means that sodium hydroxide can absorb water vapor and carbon dioxide from the air when it comes into contact with normal air.

Sodium hydroxide's uses include its use in making many soaps and detergents, making medicines like aspirin, controlling the acidity of water, dissolving unwanted materials in wood in making wood and paper products, etc.

What is aluminum hydroxide?

Aluminum hydroxide is an amphoteric hydroxide with the chemical formula Al (OH) 3 . Amphoteric means that this compound has both acidic and basic properties. Aluminum hydroxide occurs naturally as the mineral known as gibbsite .

The molar mass of aluminum hydroxide is 78 g / mol. The melting point is 300 ° C. Aluminum hydroxide appears as an amorphous white powder. When aluminum hydroxide is reacted with an acid, it acts as a Brønsted-Lowry base and accepts protons. When reacting with bases, it acts as a Lewis acid by accepting a pair of electrons from a hydroxyl anion.

Key difference - sodium hydroxide vs. aluminum hydroxide

Figure 2: Chemical structure of aluminum hydroxide

The uses of aluminum hydroxide include:

  • Raw material for the production of other aluminum compounds
  • a fire retardant filler for polymer applications
  • an antacid in humans and animals, etc.

Difference Between Sodium Hydroxide and Aluminum Hydroxide

definition

Sodium hydroxide: Sodium hydroxide is a metal hydroxide with the chemical formula NaOH.

Aluminum hydroxide: Aluminum hydroxide is an amphoteric hydroxide with the chemical formula Al (OH) 3 .

Hydroxide anions

Sodium hydroxide: In sodium hydroxide there is one hydroxide anion per sodium cation.

Aluminum hydroxide: There are three hydroxide anions per aluminum cation in aluminum hydroxide.

nature

Sodium hydroxide: Sodium hydroxide is a basic compound.

Aluminum hydroxide: Aluminum hydroxide is an amphoteric compound.

molar mass

Sodium hydroxide: The molar mass of sodium hydroxide is 39.99 g / mol.

Aluminum hydroxide: The molar mass of aluminum hydroxide is 78 g / mol.

Melting point

Sodium hydroxide: The melting point of sodium hydroxide is 318 ° C

Aluminum hydroxide: The melting point of aluminum hydroxide is 300 ° C.

Reaction with acids

Sodium hydroxide: Sodium hydroxide reacts with acids and forms a sodium salt.

Aluminum hydroxide: When aluminum hydroxide reacts with an acid, it acts as a Brønsted-Lowry base and accepts protons.

Reaction with bases

Sodium hydroxide: Sodium hydroxide does not react with bases.

Aluminum hydroxide: When reacting with bases, it acts as a Lewis acid by accepting a pair of electrons from a hydroxyl anion.

diploma

Both sodium hydroxide and aluminum hydroxide are ionic compounds made up of metal cations and hydroxide anions. The main difference between sodium hydroxide and aluminum hydroxide is that sodium hydroxide is a basic compound while aluminum hydroxide is an amphoteric compound.

Reference:

1. "SODIUM HYDROXIDE." National Center for Biotechnology Information. PubChem Compound Database, US National Library of Medicine, available here .

Image courtesy:

1. “Sodium hydroxide picture” by Hari Vinayak santhosh - Own work (CC BY-SA 4.0) via Commons Wikimedia 2. “Aluminum hydroxide” by Copsi (Public Domain) via Commons Wikimedia

About the author: Madhusha

Madhusha is a BSc (Hons) graduate in Biological Sciences and is currently doing her Masters in Industrial and Environmental Chemistry. Her areas of interest for writing and research include biochemistry and environmental chemistry.