Difference Between Acetic Acid and Glacial Acetic Acid

The key difference between acetic acid and glacial acetic acid is that the acetic acid causes no harm whereas the glacial acetic acid is corrosive and, therefore, should handle it with care.

Acetic acid belongs to the family of organic compounds known as carboxylic acids. They have the functional group –COOH. We call this functional group as the carboxyl group. On the other hand, the glacial acetic acid is the highly concentrated form of acetic acid.

CONTENTS

1. Overview and Key Difference
2. What is Acetic Acid
3. What is Glacial Acetic Acid
4. Side by Side Comparison – Acetic Acid vs Glacial Acetic Acid in Tabular Form
6. Summary

What is Acetic Acid?

Acetic acid is a carboxylic acid, which has a general formula as follows.

In the simplest type of carboxylic acid, the R group equals to H, and we call it formic acid. In addition to this formic acid, there are many other types of carboxylic acids with various R groups. Here, the R group can be a straight carbon chain, branched chain, an aromatic group, etc. Some of the examples for carboxylic acids are acetic acid, hexanoic acid, and benzoic acid.

Acetic acid is the carboxylic acid in which the R group of the above structure is –CH₃. In the IUPAC nomenclature, we name carboxylic acids by dropping the final –e of the name of the alkane corresponding to the longest chain in the acid and by adding –oic acid. Always, we assign the carboxyl carbon number 1. According to this, the IUPAC name for acetic acid is ethanoic acid. So the acetic acid is the common name of it.

As the name says, it is an acid, so can donate a hydrogen ion into a solution. It is a monoprotic acid. It is a colourless liquid with a sour taste and a characteristic smell.  Moreover, it is a polar molecule. Because of the –OH group, they can form strong hydrogen bonds with each other and with water. As a result, this acid has a high boiling point, which is about 119 °C. In addition to that, it easily dissolves in water. Since it is a carboxylic acid, it undergoes all the reactions of carboxylic acids. Since they are acidic, they react readily with NaOH and NaHCO₃ solutions to form soluble sodium salts.

Use

Acetic acid is a weak acid, and it exists in equilibrium with its conjugate base (acetate ion) in aqueous media. This acid is the main component in vinegar, which is useful in food processing. We can use it as a polar solvent to prepare solvent systems. It is also important as a chemical reagent to synthesize compounds. For example, we use it with an alcohol to produce an ester.

Synthesis

Acetic acid is naturally synthesized by anaerobic fermentation using sugar substrates. The anaerobic bacteria carry out this process. The main method of synthetically producing acetic acid is by the methanol carbonylation method.

What is Glacial Acetic Acid?

Glacial acetic acid is the undiluted form of acetic acid. It doesn’t contain any water; thus, it has 100% acetic acid only. We can dilute this acid by adding water to prepare the required concentration of acetic acid solutions. Since it is too concentrated, the acidity of glacial acetic acid is high. Therefore, it is corrosive and can damage the skin if in contact.

What is the Difference Between Acetic Acid and Glacial Acetic Acid?

Acetic acid is the acid that gives vinegar its characteristic taste. Moreover, the pure acid is a colourless viscous liquid or glassy solid while glacial acetic acid is the highest concentrated form of acetic acid. That is, the glacial acetic acid contains no or less than 1% water. In other words, undiluted or 100% concentrated acetic acid is known as glacial acetic acid. Therefore, the main difference between acetic acid and glacial acetic acid is that the acetic acid causes no harm whereas the glacial acetic acid is corrosive. Therefore, the glacial acetic acid should be handled with care.

The below infographic tabulates the difference between acetic acid and glacial acetic acid for quick reference.

Summary -Acetic Acid vs Glacial Acetic Acid

As said before, the acetic acid is a carboxylic acid. Whereas the glacial acetic acid is the most concentrated form of acetic acid. The key difference between acetic acid and glacial acetic acid is that the acetic acid causes no harm whereas the glacial acetic acid is corrosive, and should handle it with care.

Reference:

1. Helmenstine, Anne Marie, Ph.D. “What Is Glacial Acetic Acid?” ThoughtCo, Jun. 22, 2018. Available here

Image Courtesy:

1.”Acetic acid”By W. Oelen (CC BY-SA 3.0) via Commons Wikimedia