ACETIC ACID - (64-19-7)

Introduction

Name: acetic acid*; ethanoic acid; acetyl hydroxide
* IUPAC
CAS Number: 64-19-7
Chemical Formula: C2H4O2 or CH3COOH
Molar Mass: 60.05196 g
State of Matter: colorless liquid
Mass Percent: C 40.001 %; H 6.7137 %; O 53.285 % 

Classification

Uses/Function

• "…dilute solutions of the acid (such as vinegar) are harmless…" 1

• "It is used primarily to prepare acetate esters, which are substances formed by reacting acetic acid with a compound whose molecules have a O-H bond in them." 2

• "Cellulose, found in cotton and wood, is a macromolecular material (a material made up of very large molecules) containing O-H bonds. It reacts with acetic acid to give cellulose acetate for film and textile fibers" 3

• "Acetic acid is probably best known to most people as vinegar. In this form, it is used as a condiment and a food preservative. The greatest volume of acetic acid is used, however, in a variety of chemical processes, especially in the manufacture of plastic materials such as polyvinyl acetate (PVA), polyethylene terephthalate (PET), and cellulose acetate. A more recent used of acetic acid is in the manufacture of calcium magnesium acetate (CMA), a deicer. Traditionally, roads, highways, and airport runways have been treated with calcium chloride (CaCl2) or some other salt to remove snow and ice. These compounds have serious environmental effects, however, and researchers have long been looking for alternatives that are as effective in removing snow and ice, but less harmful to the environment. CMA has been the most promising of these alternatives, and its production has produced a growing demand for acetic acid. Some other applications of acetic acid include: as a cleaning agent; in the manufacture of photographic materials; for the production of a variety of organic compounds such as those used in the manufacture of packaging materials, paints, adhesives, and artificial fibers; as a fumigant (pesticide) to preserve fruits and grains; in the printing of textiles; and as an acidifier to improve the flow of oil from wells. Dilute acetic acid in the form of vinegar is harmless and has been consumed by humans for centuries. Prolonged contact with the skin or eyes may, however, produce irritation of tissues and should be avoided. Concentrated forms of acetic acid pose more serious health risks, such as irritation of the gastrointestinal system, respiratory system, and eyes. Most people do not come into contact with the concentrated acid, and safety precautions are of importance only to individuals who handle the material in their work." 4

• "...the acid in vinegar." 5

• "Manuf[acturing] various acetates, acetyl compounds, cellulose acetate, acetate rayon, plastics and rubber in tanning; as laundry sour; printing calico and dyeing silk; as acidulant and preservative in foods; solvent for gums, resins, volatile oils, and many other substances. Widely used in commercial organic syntheses. Pharmaceutic aid (acidifier). Vesicant, caustic, destruction of warts." 6

• "…the tart component of vinegar…" 7

Physical Properties

Melting Point:*
16.6°C 8 = 289.75 K = 61.88°F
Boiling Point:*
117.9°C 8 = 391.05 K = 244.22°F
Density (g/cm3):
1.0446 at 25°C 8
* - 1 atm pressure

Solubility

Qualitative:
slightly soluble: water 8
soluble: acetone 8
very soluble: ethyl ether • ethanol 8

pKa:4.74 9

Bonding

Double Bonds: 1
Triple Bonds: 0
σ Bonds: 7
π Bonds: 1
Total: 8
Carboxyl Groups: 1
Hydroxyl Groups: 0
Hybridization: carboxyl group carbon and oxygen are sp2; other carbon and oxygen are sp3

Thermochemistry

ΔHf° (ℓ): -115.71 kcal/mol 10 = -484.13 kJ/mol
ΔHf° (g): -103.93 kcal/mol 10 = -434.84 kJ/mol
S° (ℓ): 38.2 cal/(mol•K) 11 = 159.83 J/(mol•K)
S° (g): 67.52 cal/(mol•K) 11 = 282.50 J/(mol•K)
ΔGf° (ℓ): -93.2 kcal/mol 12 = -389.95 kJ/mol
ΔGf° (g): -90.03 kcal/mol 12 = -376.69 kJ/mol
The heat of combustion is the amount of heat released when one mole of a substance undergoes combustion according to the general reaction equation:
CxHyOz + 0.25(4x+y-2z) O2 (g) → x CO2 (g) + 0.5y H2O (ℓ)

ΔHcomb° (ℓ): -209.02 kcal = -874.54936 kJ
ΔHcomb° (g): -220.8 kcal = -923.83688 kJ

For More Information

Sources

(1) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 127.
(2) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 128.
(3) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 128.
(4) - Schlager, Neil, Weisblatt, Jayne, Newton, David E., and Montney, Charles B. Chemical Compounds Vol. 1; Thomson-Gale: Detroit, MI, 2006; pp 25-26.
(5) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; p 321.
(6) - The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th ed.; Budavari, S.; O'Neil, M.J.; Smith, A.; Heckelman, P. E.; Kinneary, J. F., Eds.; Merck & Co.: Whitehouse Station, NJ, 2001; entry 56.
(7) - Atkins, Peter. Reactions; Oxford University Press: Oxford, United Kingdom, 2011; p 18.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 3-5.
(9) - The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th ed.; Budavari, S.; O'Neil, M.J.; Smith, A.; Heckelman, P. E.; Kinneary, J. F., Eds.; Merck & Co.: Whitehouse Station, NJ, 2001; entry 56.
(10) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:65.
(11) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:65.
(12) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:65.