What Is Acetic Acid?
Vinegar is a household essential often used for cooking, and it even helps unclog sinks. What chemical substance makes vinegar smell the way it does? Vinegar is actually a solution that is made of 4-8% of acetic acid that is dissolved in water and other substances that give vinegar its flavor depending on its type.
Acetic acid, also known as ethanoic acid and methanecarboxylic acid, is a colorless liquid that has a strong and distinct pungent and sour smell. Its chemical formula is C2H4O2: it has two carbon (C) atoms, four hydrogen (H) atoms and two oxygen (O) atoms. Because it has a carbon in its chemical formula, it is an organic compound. Its chemical formula can be written multiple ways, as shown here:
Now that we know the chemical formula of acetic acid, let’s talk about its chemical structure. Its chemical structure is shown in the following illustration. Here, we can see two ways to draw its chemical structure (see video). On the left (1), all the carbon, hydrogen and oxygen atoms and how they are bonded to each other are shown. On the right (2), instead of writing the carbon atom, it is represented by an edge or bend in the line, and the hydrogen atoms attached to the first carbon on the left are not shown.
The chemical structure of carboxylic acid shows that the first carbon on the left has single bonds with three hydrogen atoms. The second carbon, on the other hand, has a double bond with the oxygen atom and is singly bonded with the first carbon and the -OH group.
Let’s take a closer look at the chemical structure of acid. Acetic acid is classified as a carboxylic acid. A carboxylic acid, shown as RCOOH, is a group of organic compounds that contain a carboxyl group. Here, the R group in the carboxylic acid structure may contain one or more carbon and/or hydrogen atoms. A carboxyl group is the -COOH group boxed in red. Because acetic acid contains a carboxyl group as well, it is classified as a carboxylic acid. In fact, acetic acid is also known as the second simplest carboxylic acid. In the illustration, it also shows that the R group of acetic acid contains -CH3.
Each year, a million tons of acetic acid is produced. That is a lot! While we most commonly know that acetic acid is used in vinegar, it is used for so much more, and it is a very important chemical used in many industrial processes. Let’s take a look at the various uses of acetic acid.
Acetic Acid in Vinegar
Let’s start with acetic acid’s claim to popularity: vinegar. We use vinegar for so many things – for cooking, cleaning, laundry and many other household uses, like unclogging drains. It is also used in a popular science project – the volcano science experiment – where the lava is vinegar reacting with baking soda colored in red food coloring. Vinegar is most definitely a cook’s friend. It is so important in the kitchen that we may even have many different types of vinegar: balsamic vinegar, apple cider vinegar, red and white wine vinegar, and more.
Production of Vinyl Acetate Monomer
A majority of the acetic acid that is produced is used to produce vinyl acetate monomer, or VAM. What is so important about VAM? Vinyl acetate monomer (VAM) is a building block that is used in many industries to make paints, adhesives, packaging, and more.
Production of Acetic Anhydride
Here is another major application of acetic acid; it is used to produce a chemical called acetic anhydride. What is acetic anhydride used for? The major application of acetic anhydride is to make a substance called cellulose acetate, which is used to make a cellulose acetate film that is used in photography. Acetic anhydride is also used to produce heroin as well.
Production of Ester
Acetic acid also produces esters. Below, it shows some esters produced from acetic acid, like ethyl acetate and isobutyl acetate. The esters from acetic acid are used in inks, paints, and coatings.