Acetic Acid Facts, Glacial Acetic Acid, Acetic Acid Formula, What is Acetic Acid

What is Acetic Acid

Acetic acid is a weak acid which is probably most famous for being the primary acid in vinegar. In fact, acetic acid has a wide range of uses beyond sprinkling on salads, and it is produced in large volumes all over the world. People have been working with this acid in a number of contexts for centuries, with acetic acid being one of the substances explored by alchemists, the predecessors of modern chemists.

This organic acid can be prepared in varying concentrations. In pure form, it is known as glacial acetic acid because it crystallizes in cool temperatures. This form of the acid is extremely corrosive and can be hazardous to work with, requiring special precautions for protection. Vinegar, by contrast, usually has an acetic acid concentration of around five percent.

There are a number of ways in which this acid can be prepared. One method is bacterial fermentation, the technique used to make vinegars, in which acetic acid is generated as a byproduct of bacterial digestion. Other techniques involve producing chemical reactions which result in this acid, as is done in commercial manufacture of this product. When the acid is destined for use in food, however, it is usually produced biologically because this is often required for food labeling reasons.

This clear, colorless acid has a distinctive sour taste, although tasting it is not recommended unless it is clearly labeled as fit for human consumption. It also has a strong, sharp odor which is familiar to many people because it smells like vinegar. Or, rather, vinegar smells like acetic acid. In food preparation, it can be used as a flavoring, with the sharp taste being desirable in some foods, and also as a food preservative. The acid inhibits bacterial growth, keeping food safe from contamination. The historic use of vinegar as a food preservative has created an acquired taste in some cultures for the distinctive tang of vinegar, so foods which no longer require preservation may have some added vinegar for flavor.

Industrially, acetic acid is used in a wide range of processes. It is also used in chemical production and research, in settings where people have need for a weak acid. Like other acids, acetic acid is corrosive for many substances, and it can be involved in a variety of chemical reactions. Acetic acid is used as a solvent, a reagent, a catalyst, and a pesticide. It can be used in the preparation of paints, varnishes, and glazes, and in medical treatment, as for example in the treatment of jellyfish stings.

Molecular Formula: C2H4O2

The molecular formula for acetic acid CH3COOH. The molar mass of acetic acid is 60 grams per mole. Acetic acid is formed by the reaction of methanol and carbon monoxide.

3OH + CO ------> CH3COOH
Acetic acid is also produced by the acetaldehyde oxidation. The equation for the reaction is;

4H10 + 5O2 ------ > 4CH3COOH + 2H2O

Acetic acid is formed during anaerobic fermentation. For example;

6H12O6 ------ > 3 CH3COOH

What is glacial acetic acid and how does it differ from acetic acid?

Glacial acetic acid is a trivial name for water-free acetic acid.

Usually acetic acid containing usually less than 1 percent of water. Glacial acetic acid is anhydrous form of acetic acid in which it exists in dimmer form. It's known as Glacial because on freezing it forms needle shape crystals.

The ethan- stem means you have two carbons, and the -oic acid ending means that the carbon on the end is part of a carboxylic acid group, -COOH. So ethanoic acid is CH3COOH, which is more commonly known as acetic acid.

Anhydrous (water-free) acetic acid is sometimes called glacial acetic acid because it solidifies just below room temperature, at 16.7°C. Acetic acid can be concentrated by dripping the impure compound over a "stalactite" of glacial (frozen) acetic acid. Pure acetic acid crystallizes, while impurities run off in the liquid

Uses of Acetic Acid

Apart from the production of vinegar, acetic acid or ethanoic acid has several other uses.

  • It is used for the production of vinyl acetate monomer (VAM). It is then used for production of polyvinyl acetate for application in paints and adhesives.

  • Ethanoic acid is also used for the production of several important esters, such as ethyl acetate, n-butyl acetate, isobutyl acetate, and propyl acetate, which are used for inks, paints and coatings.

  • Ethanoic acid finds application in the production of acetic anhydride [I(CH3CO)2O], which is used as an acetylating agent for the manufacture of cellulose acetate-a synthetic textile, and also for photographic films. Acetic anhydride is also an important reagent for the manufacture of products like aspirin.

  • It is also used as a solvent, for treatment of the sting of box jellyfish, as a preservative, and as an inhibitor of bacterial and fungal growth.

  • Acetic acid is used for the production of terephthalic acid (TPA), the raw material for polyethylene terephthalate.

Acetic Acid Facts

  1. Acetic acid’s claim to fame at home is vinegar. Vinegar is typically a 4-8% solution of acetic acid; the rest is water and trace amounts of other molecules that impart slightly different flavors to different types of vinegar.

  1. While the name acetic acid is accepted by IUPAC, you can also call it ethanoic acid if you strictly follow the basic IUPAC naming system.

  1. Make a volcano with vinegar and baking soda. One of the most important uses for household acetic acid is to make a volcano science project. All you need is a volcano model, some vinegar, some baking soda (sodium bicarbonate), and probably some red food coloring if you really want the molten lava look. The acetic acid reacts with the sodium bicarbonate to generate a bunch of CO2 – this bubbles off to give the volcano effect.

  1. The acetic acid in vinegar is formed by the fermentation of ethanol. This reaction requires oxygen from the air, which is why opened bottles of wine taste vinegary after a while, even though unopened bottles of wine can keep for ages.

  1. There is an estimated global demand for acetic acid of 6.5 million metric tons. This comes out to about 1 kilo of acetic acid per person. If this was due to vinegar consumption, this value would correspond to 5 gallons of vinegar per person per year. That is clearly not accurate; it turns out most of the acetic acid in the world is being used for other things.

  1. The main use for acetic acid is to make vinyl acetate, which can then be used to make the polymer polyvinylacetate, or PVA. This polymer is used in many glues, including yellow “carpenter’s glue”.

  1. Most acetic acid is not made by fermentation. Industrially, it is usually made from methanol by the Monsanto process, which features a rhodium catalyst for a key carbonylative step.

  1. Concentrated acetic acid is often called “glacial acetic acid”. The origin of this name can be attributed to acetic acid’s high freezing point. Acetic acid freezes into a solid at a temperature very close to room temperature: 16.5 ºC, or 62 ºF. When it freezes, it kind of looks like ice; hence the term “glacial”.

  1. At home, vinegar has some very practical uses besides salad dressing. It can be used to remove limescale – the ugly white minerals that accumulate over time from hard water. For example, tea kettles and shower heads can benefit from a vinegar soak.

  1. Wash fruits and veggies with vinegar. One of the most effective ways to wash fruits and veggies is with dilute vinegar. In one study, a dilute vinegar wash removed 98% of the bacteria from fruit skins, compared to 85% removal with water and a scrub brush alone.
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