Acetic Acid

A summary of the most common chemical descriptors (InChI Key and SMILES codes) for Acetic Acid are summarized together with 3D and 2D structures and relevant physico-chemical properties.

What is the Acetic Acid?

The molecule Acetic Acid presents a molecular formula of C2H4O2 and its IUPAC name is acetic acid.

Acetic acid is a molecule with the chemical formula CH3COOH. It is a weak acid, meaning that it only partially dissociates into its ions in water. The rest of the molecule remains as the "parent" molecule. The parent molecule is called the "conjugate base" of the acid..

The conjugate base of acetic acid is the acetate ion, CH3COO-. When acetic acid dissolves in water, it releases hydronium ions, H3O+. The hydronium ions increase the acidity of the solution..

The dissociation of acetic acid is represented by the following equation:.

CH3COOH + H2O <=> CH3COO- + H3O+.

The K_a for acetic acid is 1.8 x 10-5. This means that, at 25 degrees Celsius, the concentration of hydronium ions in a solution of acetic acid is 1.8 x 10-5 times the concentration of acetic acid..

In other words, for every molecule of acetic acid that dissociates, 1.8 x 10-5 molecules of hydronium ions are produced..

The K_b for the conjugate base, acetate, is 1.3 x 10-10. This means that, at 25 degrees Celsius, the concentration of hydroxide ions in a solution of acetate is 1.3 x 10-10 times the concentration of acetate..

In other words, for every molecule of acetate that dissociates, 1.3 x 10-10 molecules of hydroxide ions are produced..

The pH of a solution of acetic acid can be calculated using the following equation:.

pH = -log[H3O+].

where [H3O+] is the concentration of hydronium ions in the solution..

Using the K_a value for acetic acid, we can calculate the [H3O+] as follows:.

[H3O+] = 1.8 x 10-5 * [acetic acid].

where [acetic acid] is the concentration of acetic acid in the solution..

Plugging this value into the equation for pH, we get:.

pH = -log(1.8 x 10-5 * [acetic acid]).

pH = 4.74 - log[acetic acid].

This equation shows that the pH of a solution of acetic acid is directly proportional to the concentration of acetic acid in the solution..

The pH of a 0.1 M solution of acetic acid is 4.64. The pH of a 0.01 M solution of acetic acid is 3.64. The pH of a 0.001 M solution of acetic acid is 2.64..

The pH of vinegar, which is a dilute solution of acetic acid, is typically between 2.4 and 3.4..

3D structure

Cartesian coordinates

Geometry of Acetic Acid in x, y and z coordinates (Å units) to copy/paste elsewhere. Generated with Open Babel software.

2D drawing

 

Acetic Acid QTBSBXVTEAMEQO-UHFFFAOYSA-N chemical compound 2D structure molecule svg
Acetic Acid

 

Molecule descriptors

 
IUPAC nameacetic acid
InChI codeInChI=1S/C6H10O4/c7-5(8)3-1-2-4-6(9)10/h1-4H2,(H,7,8)(H,9,10)
InChI KeyQTBSBXVTEAMEQO-UHFFFAOYSA-N
SMILESC(=O)(O)C

Other names (synonyms)

IUPAC nomenclature provides a standardized method for naming chemical compounds. Although this system is widely used in chemistry, many chemical compounds have also other names commonly used in different contexts. These synonyms can come from a variety of sources and are used for a variety of purposes.

One common source of synonyms for chemical compounds is the common or trivial names, assigned on the basis of appearance, properties, or origin of the molecule.

Another source of synonyms are historical or obsolete names employed in the past, however replaced nowadays by more modern or standardized names.

In addition to common and historical names, chemical compounds may also have synonyms that are specific to a particular field or industry.

Reference codes for other databases

There exist several different chemical codes commonly used in orded to identify molecules:

Physico-Chemical properties

IUPAC nameacetic acid
Molecular formulaC2H4O2
Molecular weight60.052
Melting point (ºC)17
Boiling point (ºC)118
Density (g/cm3)1.050
Molar refractivity13.50
LogP0.1
Topological polar surface area74.6

LogP and topological polar surface area (TPSA) values were estimated using Open Babel software.

The n-octanol/water partition coeficient (Kow) data is applied in toxicology and drug research. Kow values are used, to guess the environmental fate of persistent organic pollutants. High partition coefficients values, tend to accumulate in the fatty tissue of organisms. Molecules with a log(Kow) (or LogP) greater than 5 are considered to bioaccumulate.

TPSA values are the sum of the surface area over all polar atoms or molecules, mainly oxygen and nitrogen, also including hydrogen atoms.

In medicinal chemistry, TPSA is used to assess the ability of a drug to permeabilise cells.

For molecules to penetrate the blood-brain barrier (and act on receptors in the central nervous system), TPSA values below 90 Å2 are required. Thus, molecules with a polar surface area greater than 140 Å2 tend to be poorly permeable to cell membranes.