Difference Between Aluminate and Meta Aluminate

The key difference between aluminate and meta aluminate is that aluminate is an oxide anion, whereas meta aluminate is a hydroxide anion.

Aluminate and meta aluminate are two types of anions which are related to each other depending on their chemical structure. However, their atomicity is different from each other. This is because aluminate anion has only oxygen atoms in association with aluminum atoms, whereas meta aluminate contains both hydrogen and oxygen atoms in association with aluminum atoms.

CONTENTS

1. Overview and Key Difference
2. What is Aluminate
3. What is Meta Aluminate
4. Side by Side Comparison – Aluminate vs Meta Aluminate in Tabular Form
5. Summary

What is Aluminate?

Aluminate is an oxyanion of aluminum having the chemical formula AlO₄^–. The most common compound containing aluminate anion is sodium aluminate. Furthermore, pure sodium aluminate is an anhydrous compound that appears as a white crystalline solid. Meanwhile, the hydrated sodium aluminate occurs as a hydroxide compound. And, the most common hydrated sodium aluminate form is the tetrahydroxyaluminate of sodium.

Moreoer, aluminate anion is a polyatomic anion containing an aluminum atom at the center of the anion and four oxygen atoms attached to this central aluminum atom via covalent bonds. The charge of the anion is -1. The molar mass of the anion is 91 g/mol.

What is Meta Aluminate?

Meta aluminate is the hydrated form of aluminate anion. Therefore, aluminate is an oxyanion while meta aluminate is a hydroxide anion. The chemical formula of this anion is Al(OH)₄^–. Also, the molar mass of this anion is 95 g/mol. Moreover, one meta aluminate anion forms when two water molecules come into association with an aluminate anion.

Normally, AlO₂^– ion is called “meta” while the AlO₃^3- ion is called the “ortho” compound. The ortho, para and meta conformations of aluminate ions differ from each other depending on the condensation degree. The term “meta” refers to the least hydrated form of sodium aluminate.

What is the Difference Between Aluminate and Meta Aluminate?

Aluminate and meta aluminate are two related anionic forms. The key difference between aluminate and metal aluminate is that aluminate is an oxide anion, whereas meta aluminate is a hydroxide anion. Also, the chemical formula of aluminate is AlO₄^– while the chemical formula of meta aluminate is Al(OH)₄^–.

Moreover, the aluminate anion is an oxyanion while the meta aluminate is a hydrated oxyanion. So, this is another difference between aluminate and metal aluminate. Furthermore, the molar mass of aluminate is 91 g/mol, while the molar mass of meta aluminate is 95 g/mol.

Depending on the composition, we can call aluminate an oxyanion (contains aluminum and oxygen atoms) while meta aluminate can be categorized as a hydroxyanion (contains aluminum in combination with oxygen and hydrogen atoms). Sodium aluminate is a well-known example of a compound containing an aluminate anion while sodium meta aluminate is an example of a compound containing a meta aluminate anion.

Below infographic summarizes the difference between aluminate and metal aluminate.

Summary – Aluminate vs Meta Aluminate

Aluminate and meta aluminate are two related anionic forms. The key difference between aluminate and metal aluminate is that aluminate is an oxide anion, whereas meta aluminate is a hydroxide anion. Therefore, aluminate is called an oxyanion and meta aluminate is called a hydroxyanion. The chemical formula of aluminate anion is AlO₄^– while the chemical formula of meta aluminate anion is Al(OH)₄^–.

Reference:

1. “Aluminate.” Wikipedia, Wikimedia Foundation, 4 Sept. 2019, Available here.
2. “Aluminate.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
3. “Sodium Aluminate.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.

Image Courtesy:

1. “NaAlO2” By Leiem – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Tetrahydroxoaluminate ion” By Leyo – Own work (Public Domain) via Commons Wikimedia