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General |
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| Name | Propionic acid | |
| Chemical formula | C3 H6 O2 | |
| Formula weight | 74.08 amu | |
| Synonyms | propanoic acid, ethanecarboxylic acid, methylacetic acid, ethylformic acid | |
| CAS number | 79-09-4 | |
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Phase behavior |
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| Melting point | 252 K (-21 °C) | |
| Boiling point | 414 K (141°C) | |
| Critical point | 607 K (334°C) 46.7 bar |
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| Liquid density | 0.99 ×103 kg/ mFor other uses of "metre" and "meter", see Metre (disambiguation). The metre is the basic unit of length in the International System of Units (SI: Systeme International d'Unites). It is defined as the length of the path travelled by light in absolute vacu3 | |
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Acid-base properties |
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| pKaIn chemistry and biochemistry, the acidity constant or acid dissocation constant is a specific type of dissociation constant that indicates the extent of dissociation of hydrogen ions from an acid. An acid with an acidity constant much greater than 1 is a | 4.88 | |
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Liquid thermochemistry |
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| ΔfH0liquidThe standard enthalpy of formation of a compound is the change of enthalpy that accompanies the formation of 1 mole of that substance from its component elements, at their standard states (the most stable form of the element or compound at 25 degrees Cels | -510.8 kJThe joule (symbol J also called newton metre or coulomb volt is the SI unit of energy and work. The unit is pronounced to rhyme with "tool", and is named in honour of the physicist James Prescott Joule (1818-1889). 1 joule 1 N · 1 m 1 newton · 1 metre 1 k/ molThe mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry. It measures the amount of substance of a system and is defined as the amount of substance that contains as many elementary entities as there are atoms in exactly 0 | |
| S0liquidIn chemistry, the standard molar entropy is the entropy content of one mole of substance, under conditions of standard temperature and pressure. By comparing the entropies of products and reactants in a chemical reaction, we can determine whether the reac | 191.0 J/mol·K | |
| ΔfusHHeat of fusion is the heat absorbed by a unit mass of a solid chemical element at its melting point in order to convert the solid into a liquid at the same temperature. The heat of fusion is equal to the heat of solidification. The energy that goes into m | 10.6 kJ/mol | |
| ΔfusSThe Entropy of fusion of a substance represents the increase in the degree of disorder involved in the transition from an organized crystalline solid to the disorganized structure of a liquid. It is denoted as ΔS and normally expressed in J / mol · | 42.2 J/mol·K | |
| Cp | 158.6 J/mol·K | |
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Gas thermochemistry |
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| ΔfH0gas | ? kJ/mol | |
| S0gas | ? J/mol·K | |
| ΔvapH | 55 kJ/mol | |
| Cp | ? J/mol·K | |
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Safety | ||
| Acute effects | Corrosive. Contact with concentrated liquid can result in permanent damage to skin, eyes, or digestive tract. | |
| Chronic effecs | None known. | |
| Flash point | 55°C | |
| Autoignition temperature | 475°C | |
| Explosive limits | 3-15% | |
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More info | ||
| Properties | NIST WebBook | |
| MSDS | Hazardous Chemical Database | |
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SI units were used where possible. Unless otherwise stated, standard conditions were used. | ||
The chemical compound propionic acid (systematically named propanoic acid) is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. In the pure state, it is a colorless, corrosive liquid with a sharp, somewhat unpleasant odor.
It is produced biologically from the metabolic breakdown of fatty acids containing odd numbers of carbon atoms, and also it the breakdown of some amino acids. Bacteria of the genus Propionibacterium produce propionic acid as the end product of their anaerobic metabolism. These bacteria are commonly found in the stomachs of ruminants, and their activity is partially responsible for the odor of both swiss cheese and sweat.
Priopionic acid was first described in 1844 by Gottlieb, who found it among the degradation products of sugar. Over the next few years, other chemists produced propionic acid in various other ways, none of them realizing they were producing the same substance. In 1847, the French chemist Jean-Baptiste Dumas established that all the acids were the same compound, which he called propionic acid, from the Greek words protos and pion, meaning "first" and "fat" respectively, because it was the smallest acid that exhibited the properties of the other fatty acids, such as producing an oily layer when salted out of water and having a soapy potassium salt.
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